International Journal of Abdominal Wall and Hernia Surgery

: 2021  |  Volume : 4  |  Issue : 4  |  Page : 174--180

An observational study of short- and long-term complications including pain after onlay mesh umbilical hernia repair

Andrew Mark McCombie1, Debbie Osborn2, Ross Roberts3,  
1 Department of General Surgery, Canterbury District Health Board Christchurch, Christchurch, New Zealand; Department of Surgery, University of Otago, Christchurch Campus, New Zealand
2 Hernia Clinic, Christchurch, New Zealand
3 Department of General Surgery, Canterbury District Health Board Christchurch, Christchurch, New Zealand; Hernia Clinic, Christchurch, New Zealand

Correspondence Address:
Dr. Andrew Mark McCombie
Department of General Surgery, Canterbury District Health Board (CDHB), University of Otago, Private Bag 4710, Christchurch 8140.
New Zealand


BACKGROUND: Information about outcomes for patients who undergo onlay mesh placement for umbilical hernia repair is scarce and the factors that influence adverse outcomes, such as long-term pain, are not well understood. A study of patients undergoing open umbilical hernia repair was undertaken. MATERIALS AND METHODS: Patients who underwent open umbilical hernia repair through a private surgical practice over a 13-year period using either an onlay mesh or suture alone repair were given a questionnaire following surgery to document the incidence of long-term pain or other complications. Data were then analyzed to understand any potential contributors to a poor outcome. RESULTS: The information on 346 patients was available for study. Mesh was used for repair in 327 (94.5%) patients, whereas 19 (5.5%) had suture alone repair. Early (≤30 days) complications were experienced by 73 patients (21.1%). The most common complications were seroma formation (27 patients), wound infection (13 patients), and hematoma (11 patients). Four patients developed a combination of hematoma, infection, and seroma formation. Late (>30 days) complications (other than persistent pain) were recorded for nine patients and were all wound-related problems. Long-term pain was significantly more common in those patients reporting wound complications (odds ratio: 7.01, 95% confidence interval 1.82–26.99). Recurrent umbilical herniation developed in three patients (0.9%). CONCLUSION: Onlay mesh repair for umbilical hernia repair can be performed with low rates of chronic pain and low recurrence rates; however, surgical site occurrences remain common albeit easily treatable.

How to cite this article:
McCombie AM, Osborn D, Roberts R. An observational study of short- and long-term complications including pain after onlay mesh umbilical hernia repair.Int J Abdom Wall Hernia Surg 2021;4:174-180

How to cite this URL:
McCombie AM, Osborn D, Roberts R. An observational study of short- and long-term complications including pain after onlay mesh umbilical hernia repair. Int J Abdom Wall Hernia Surg [serial online] 2021 [cited 2022 May 18 ];4:174-180
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Umbilical hernia (UH) repair is commonly performed and most patients experience good outcomes postoperatively. The optimal repair technique has however been debated with uncertainty about the role of mesh, the surgical approach, and anatomical layer to place mesh if used. It has now been proven[1] that even for smaller UH (1–4 cm), mesh repair offers a lower recurrence rate (4%) than suture repair (12%).

The available literature lacks strong evidence informing surgeons on those issues and the risk factors for wound complications, long-term pain, and hernia recurrence after open repair.

A study of patients undergoing open UH repair was undertaken.

 Materials and Methods

Study design

This is a longitudinal study measuring short- and long-term complications as well as pain in patients with UH. Ethical approval was granted by the University of Otago Health Ethics Committee (reference HD20/041).


A prospective database of patients having UH repairs was maintained in a private two surgeon practice from March 13, 2003 to March 27, 2019. Patient demographics, method of repair, the preoperative and postoperative pain scores, and complications following surgery were recorded.


All patients who underwent UH repair during the study period were sent a questionnaire 1 year following surgery (and subsequent to June 30, 2009 a follow-up questionnaire was also sent if the initial request was not responded to). The patients that responded to the questionnaire had consented to their information being collected and stored for study purposes. Patients who did not respond to the initial or subsequent questionnaire were excluded. Complications following surgery were recorded from the time of surgery until June 2020.

Data collection

The following data were entered into the database: age, gender, size of the hernia, whether surgery was for a primary repair or for hernia recurrence, date of procedure, operating surgeon, suture or mesh repair, if mesh used––type of mesh, mesh fixation technique, use of abdominal binder or not, plus adverse outcomes including wound complications, and recurrence. Seroma, wound infection, or hematoma complications were recorded based on findings at the initial 1 week postoperative visit or subsequently irrespective of whether any surgical intervention was required. Any further surgical treatment for complications was recorded. The European Hernia Society classification for primary abdominal wall hernias[2] defines midline hernias from 3 cm above to 3 cm below the umbilicus as UH and this definition was applied to this study as well.

Pain questionnaires

Preop pain was recorded from July 31, 2013. A questionnaire was completed asking if the patient experienced any pain or not and if pain was present whether this was mild, moderate, or severe.

Pain following surgery (at 1 year or later) was measured using a questionnaire asking the patient if they experienced any pain or not and if pain was present whether this was mild, moderate, or severe.

Patients were also asked if they had developed any complications directly related to their operation and for any other comments. Finally, patients were asked if they had developed symptoms indicating a hernia at another site.

Surgical method

Two different techniques for onlay mesh placement were used. Surgeon A (86 patients) closed the primary defect with a permanent suture and then placed an onlay mesh which was secured at the margins using interrupted sutures [Figure 1]. Surgeon B (260 patients) used interrupted braided permanent sutures (0 Ethibond) placed through the edge of a folded circle of polypropylene mesh [Figure 2] to close the primary defect and then the mesh margins were secured with 2/0 Prolene sutures [Figure 3]. This technique allows the mesh to act as a pledget to prevent suture tearing of the fascia [Figure 4]. A compression dressing consisting of a gauze square placed within the umbilicus and covered by a plastic dressing (Tegaderm) was applied and an elasticated abdominal binder was used on 325 patients for at least 1 week to reduce the risk of seroma and/or hematoma formation. The wound was inspected within 1 week after surgery and any seroma (or other complication) was managed and the outcome recorded in the database.{Figure 1} {Figure 2} {Figure 3} {Figure 4}

The polyester mesh used was a lightweight, macroporous material (Parietex), and the polypropylene mesh product (Ultrapro) was a combination of polypropylene and absorbable poliglecaprone––25 monofilaments in approximately equal proportions with large pore sizes (3–4 mm) and a weight of 28 g/m2.

The mesh size allowed an approximately 3 cm overlap on each side of the defect. Larger defects required a larger mesh.

Statistical methods

We used Microsoft Excel (2013)[3] to calculate means and standard deviation (SD) and cross-tabulate frequencies. The R statistical program was used to calculate chi-square tests for independence and odds ratios (ORs) with 95% confidence intervals (CIs).[4]



During the study period, 494 patients underwent UH repair. A total of 141 patients did not respond to the postoperative questionnaire and were excluded from the study, whereas a further seven responded but did not have a complete response, thus leaving 346 patients for study purposes (70.0% response rate). Three hundred and thirty-six (97.1%) were considered primary hernia as 10 (2.9%) patients had surgery for the same site recurrence. Sixteen patients (4.6%) developed their UH postinjury (Accident Compensation Corporation New Zealand funded) with the rest considered spontaneous hernia (95.4%).

Males accounted for the majority of study patients at 295 cases (85.3%) [Table 1]. The mean age of patients was 55.63 (SD = 11.23). Large hernia (≥4 cm in size) were seen in only 63 patients (18.2%). Mesh was used for repair in 327 (94.5%) patients, whereas 19 (5.5%) had suture alone repair of smaller hernia. Of those that had mesh placed, polypropylene mesh was used for 271 (78.3%) patients, whereas 57 (16.5%) had polyester mesh placed.{Table 1}


The most common complications were seroma formation (7.8%), wound infection (3.8%), and hematoma (3.2%) [Table 2]. Four patients (1.2%) developed a combination of hematoma, infection, and seroma formation. Two patients required further surgical treatment and drainage for infection (0.58%). All noninfected seromas were treated by aspiration alone. Recurrent umbilical herniation developed in three patients (0.87%). Two followed previous suture repair––one 2 months and one 54 months earlier. One followed mesh repair 12 months earlier and so one out of 327 people (0.31%) who had mesh repair experienced recurrence. Two of these three recurrent hernia followed wound infection complicating the initial repair. Late (>30 days) complications (other than persistent pain) were recorded for nine patients (2.6%) and were all wound-related problems.{Table 2}

The incidence of complications was not significantly related to the size of the hernia (short-term complications for smaller hernia ≤4 cm 24.1% incidence vs. >4 cm 28.6% incidence, OR = 1.66, 95% CI 0.8–3.09 and long-term complications ≤4 cm 3.2% incidence vs. >4 cm 3.2% incidence, OR = 1.0, 95% CI 0.21–4.74).


At the time of their follow-up questionnaire, 56 (16.2%) responded that they still experienced pain [Table 3]. Mild pain was recorded by 41 patients (11.8%), moderate pain by 11 patients (3.2%) and severe pain by 4 patients (1.2%).{Table 3}

Preoperative pain questionnaires were completed by 86 patients and of these 38 (44.2%) had no pain, 32 (37.2%) had mild pain, 14 (16.3%) had moderate pain, and 2 (2.3%) were experiencing severe pain.

By June 2020, 86 patients had completed both the pre and postoperative (at least 1 year after surgery) pain questionnaires. Of these 41 (47.7%) reported an improvement in their pain severity, 38 (44.2%) recorded no difference and 7 patients (8.1%) recorded more pain than they experienced presurgery. Of the 38 patients who reported no difference in pain, 32 (84.2%) had no pain at baseline and so were subject to a floor effect. Amongst those with at least mild pain at baseline, 41 (85.4%) had an improvement in their pain levels and only 1 (2.6%) deteriorated.

A strong association between the development of long-term wound complications and the experience of pain at the time of the postoperative questionnaire was noted (OR: 7.01,1 95% CI 1.82–26.99).

Operating surgeon was not a predictor of outcome with pain at the time of the postoperative questionnaire (surgeon A 15.1% vs. surgeon B 16.5%, χ2 = 0.02, P = 0.89).

After June 30, 2009 nonresponding patients were repeatedly contacted to improve the response rate. The response rate did not appear to bias the reporting of pain scores. The pre July 1, 2009 group (response rate 95/71+95 = 65.0%) reported pain at the time of the questionnaire in 15 cases (15.8%), whereas the post June 30, 2009 (response rate 251/70+251 = 78.2%) reported pain in 16.3% of cases (χ2 < 0.01, P = 1.00).

Those who had follow-up at more than 1 year versus 1 year did not differ in terms of current pain (OR = 0.86, 95% CI 0.49–1.53), short-term complications (OR = 1.21, 95% CI 0.71–2.04), or long-term complications (OR = 1.35, 95% CI 0.39–4.71).


Open onlay mesh placement is considered a straightforward technique; however, the approach requires subcutaneous dissection to expose the muscle fascia that may cause seroma or hematoma formation and consequently result in surgical site infection. Mesh can also be placed in a preperitoneal or sublay position.[5]

Although some authors have reported a reduced recurrence rate after incisional hernia repair using a sublay technique when compared to an onlay method, that benefit has not been convincingly showed for UH repair. A 2019 publication on para-UH repair concluded that the onlay and sublay techniques did not significantly differ in terms of wound complications or recurrence rate but that onlay mesh repair was associated with a shorter duration of operation and length of hospital stay.[6]

With the widespread adoption of mesh repair for hernia surgery, recurrence is now less common and postoperative pain has become the most concerning long-term risk. The factors that influence the occurrence of long-term pain after UH repair are not well understood. A retrospective analysis[7] of 216 patients (with 13 patients in the open mesh repair sublay technique group and 15 patients in the laparoscopic group) who underwent elective surgery for UH during a 10-year period showed the overall hernia recurrence rate was 13.1%. Notably, only 2 (1.7%) patients with small hernias (< 2 cm) developed a recurrence. Body mass index >30 kg/m2, diabetes, and wound infection were independent risk factors for UH recurrence.

Laparoscopic UH repair requires additional port site wounds which in turn may result in herniation. Placement of intraperitoneal mesh risks formation of adhesions and bowel injury and then fistula formation.

Reinpold et al.[8] have reported excellent outcomes in a large series of 520 primary UH repairs using the MILOS (Mini/Less Open Sublay) or the EMILOS (Endoscopic Mini/Less Open Sublay)––method. The recurrence rate 1 year after MILOS/EMILOS UH repair was 0.0% with a low complication incidence. The EMILOS-technique was first reported in 2016 by R. Bittner`s group.[9] The EMILOS-operation is begins transhernially via a small incision comparable to the MILOS-technique, but after reduction of the hernia sac and creating a small retromuscular space the skin incision is closed and the operation continues endoscopically. The technique combines the advantages of open sublay and of the laparoscopic IPOM repair but avoids their disadvantages.

More recently described methods for UH repair do not, as yet, have long-term follow-up data or randomized studies but there are short-term reports such as that of one with 10 patients with UH who underwent total endoscopic sublay (TES) repair with an average operative time was 109.5 min. The authors report a mean postoperative hospital stay was 2.2 day (range, 1–4 days).[10] Another study of 26 epigastric midline ventral hernias using TES reported the procedure to be safe and reliable.[11] No significant advantages over more traditional repairs methods are evident from those data. Other techniques have been described in the literature including PUMP,[12] IPOM,[13] and eTEP.[14]

Direct open UH repair remains the most common approach currently.

UH larger than 4 cm in size are generally classified as “large” and repair of these larger hernia may be associated with an increased risk of operative complications.

Recently published international guidelines for umbilical and epigastric hernia repair[15] have made the “strong” recommendation that mesh is used to repair umbilical and epigastric hernias as it reduces recurrence. The evidence is limited for defects under 1 cm and so in these cases sutured repair could be considered in consultation with the patient. These guidelines also include the “weak” recommendations shown in [Table 4]. The authors state that there is a lack of evidence to inform which specific suture type and technique should be used for sutured repair of umbilical or epigastric hernias. Moreover, “for open repair of small and medium-sized umbilical and epigastric hernias, the optimal mesh layer, size of mesh overlap, and whether or not the defect should be closed are unknown factors that could influence outcomes, and which could be assessed in either database studies or RCTs.”{Table 4}

A randomized trial[1] comparing suture repair alone against mesh repair of UH from 1 to 4 cm in size using a flat polypropylene mesh placed in the preperitoneal plane showed a different pattern of postoperative outcomes to those reported in our study. Seroma formation was only recorded in 1 patient (<1%) in the suture alone group and in 3% of the mesh repair group. Hematoma and wound infection also occurred in a maximum of 2% of either patient group. This difference in outcome might be in part due to the difference in follow-up as those patients were first examined 2 weeks following surgery. Importantly hematoma was defined as an accumulation of blood in the wound area that warranted surgical exploration and intervention. This is a higher threshold than in our study. Patients in our study group were seen within 1 week after surgery and minor complications such as seroma or hematoma can resolve spontaneously with time.

A smaller retrospective study of 58 patients with para-UH evaluating the outcome of para-UH repair with onlay prolene mesh and followed up for 1–6 years reported superficial surgical site infection in 6 patients (10.3%).[16] Seroma was found in just one patient (1.7%). One patient (1.7%) had a recurrent hernia after 19 months. The authors of that study concluded that “mesh onlay repair by open surgery can be applied to all sizes of para umbilical hernias, it has low recurrence rate and the rates of morbidity and recurrence are comparable with international standard [sic].”

A cohort study with questionnaire and clinical follow-up of one thousand three hundred thirteen participants was conducted for patients undergoing primary, elective, open mesh, or sutured repair for a small umbilical or epigastric hernia (≤2 cm).[17] The total cumulated recurrence rate after primary repair was 10% for mesh repair and 21% for sutured repair (P = 0.001). The incidence of chronic pain was 6% after mesh repair and 5% after sutured repair (P = 0.711). The authors found that recurrence was the only independent risk factor for chronic pain. A recent publication[18] of a retrospective investigation of the outcomes of laparoscopic versus open UH repair in obese patients found that there were significantly more surgical site infections in the open approach group (1.5% vs. 0.9%) but no significant difference in wound disruption or return to the operating room. Increased morbidity overall was seen in female patients and those with a higher BMI. Long-term data were not available for this study (30-day outcomes only) and late complications such as adhesion formation, hernia recurrence, chronic pain, and mesh complications (e.g., late infection and fistula formation) could not be evaluated.

A systematic review and meta-analysis of mesh versus suture repair of UH concluded that the use of mesh reduced the risk of recurrence (risk ratio 0.48); however, the use of mesh was associated with a higher risk of seroma (risk ratio 2.37) but no increase in the risk of infection, hematoma or chronic pain.[19]

This study has confirmed that onlay mesh repair of a UH is associated with a low risk of hernia recurrence and significant complications. Long-term pain (after at least 1 year postsurgery) is uncommon and wound complications are relatively minor when precautions such as application of a pressure dressing and an abdominal binder are used. The techniques used are straightforward and do not require creation of further abdominal wall defects (as required for laparoscopic repair). With mesh placed in the prefascial plane (onlay) foreign material is not in contact with abdominal viscera and can be removed easily if required. The further important outcomes include a very low hernia recurrence rate (0.87%) of which only one occurred following mesh repair (0.31% of those with mesh repair) and a low re-operation rate for complications (0.58%). Although seromas were commonly diagnosed at short-term follow-up these were all managed by simple aspiration. These results should be compared to those reported by Venclauskas et al.,[7] where they report a recurrence rate of 18.4% after open mesh repair of a UH.

Importantly, these data show that long-term pain is correlated with long-term wound complications and techniques to minimize these adverse outcomes are therefore an important component of surgical technique and postoperative follow-up.

The limitations of the study include the fact that to date only 74 patients have completed both their preoperative and postoperative questionnaires, the nonrandomized nature of the study, and the subjective nature of patient-reported outcomes.

Strengths of the study include the long duration of the study (13 years) with a consistent approach to surgical approach and follow-up. A relatively high percentage of patients completed the postoperative questionnaire. Our data from two periods of follow-up with different follow-up rates suggest that the nonresponders did not significantly bias the results.


Onlay mesh repair for UH repair can be performed with low rates of chronic pain and low recurrence rates; however, surgical site occurrences remain common albeit easily treatable.



Authors’ contribution

All of the authors have contributed to the following: (1) concept and design of study or acquisition of data or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content; and (3) final approval of the version to be published.

Author statement

This manuscript has been read and approved by all the authors. The requirements for authorship have been met. Each author believes that the manuscript represents honest work.

Financial support and sponsorship


Conflicts of interest

Dr. Ross Roberts was “Surgeon B” for this study.

Dr. Ross Roberts is an Editorial Board member of International Journal of Abdominal Wall and Hernia Surgery. The article was subject to the journal’s standard procedures, with peer review handled independently of this Editorial Board member and their research groups.


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