The European Hernia Society defines PUH’s as ventral abdominal hernias that are located within 3 cm of the umbilicus.¹Approximately 6% to 14% of all adult abdominal wall hernias are PUH, which are second only to inguinal hernias in frequency. Over time, there has been an increase in the number of procedures done to treat these hernias. Because they have no noticeable or troublesome symptoms, most of these individuals choose not to seek treatment. In the long run, however, 65% of patients with an umbilical hernia will seek treatment for various reasons.^{2, 3}

In 1901, William James Mayo initially detailed the surgical method for this condition, and it continued to be the preferred procedure.⁴ Since the late 1990s, synthetic mesh repair has replaced the conventional Mayo's suture-only repair because it yields superior long-term outcome.

For ventral hernias, mesh reinforcement has been shown to yield superior long-term results than suture-only repair.⁵But the best location for it in the musculo-aponuerotic layers of the anterior abdominal wall has long been up for discussion. There are multiple anatomical planes where the mesh could be positioned. As shown in the figure 1, these different positions are onlay position (A), inlay position (B), sublay position (C), or inlay position (D).

The mesh is secured to the exposed anterior rectus fascia during onlay repair. Placing the mesh in line with the defect and securing it around the fascia's margins is known as inlay repair.
When the mesh is positioned between the rectus muscle and posterior rectus sheath, it is known as retro rectus, preperitoneal, or Rives-Stoppa's technique. In the underlay repair, mesh is positioned intra peritoneal and anchored to the peritoneum and posterior rectus sheath.

The position of the mesh with respect to the musculo-aponeurotic layer of the abdominal wall has been the subject of much debate. However, for smaller hernias with defects less than 3 cm, many surgeons favor the onlay technique. The sublay technique is preferred if the defect is large (greater than 3 cm) or recurrent hernias. The surgeon's comfort level and personal preferences also play a role in selecting the best technique for a particular case.

The most widely used mesh repair methods for PUH in daily practice are onlay and sublay repairs.There are several benefits to sublay repair. It is argued that sublay mesh placement is associated with fewer recurrences and surgical site infections (SSI) because the mesh is covered by native tissue on both sides: fascia and muscle anteriorly and fascia posteriorly. This is thought to protect the mesh from exposure to superficial SSI’s and intra-peritoneal infections.

Onlay repair, however, has some advantages over sublay repair, such as being easier, quicker, and requiring less training.

Because it leads to fewer wound-related complications and recurrence rates, the sublay procedure is preferred as the surgery of choice for PUH in the literature that is currently available. There are, however, numerous studies in the literature that indicate that these differences are not statistically significant.

Due to the lack of compelling evidence regarding the preferred method, we chose to compare the onlay and sublay techniques in our recently opened rural hospital in order to examine a number of statistical factors and present the results of our study.

A newly established rural medical college hospital served as the study's site. From January 2023 to March 2024, a retrospective observational study was carried out. Cases were identified using the unique hospital code for paraumbilical hernias, and case files were obtained from the medical record department. The study obtained ethical clearance from institutional ethical committee.  A total of 85 cases of operated adult para umbilical hernias were identified. Case records with complete documentation were divided into two groups. Group A consists of subjects who underwent onlay repairs, while group B consists of sublay repairs. After carefully evaluating and applying inclusion and exclusion criteria, we were able to collect and assign 35 cases to each arm. The subjects' demographics, operating time, immediate post-operative wound complications, and recurrence were among the statistical parameters that were noted, tabulated, and evaluated for statistical significance. Participants included in the study were patients with paraumbilical hernias between the ages of 18 and 70 who underwent elective surgery and had a minimum follow-up period of six months. Excluded from the study were cases of paraumbilical hernia with documented ascites, chronic kidney disease, chronic liver disease and cases that were operated on emergency basis for complicated PUH.

Surgical Technique

Onlay technique

A subumbilical transverse elliptical incision was made to reach the hernia sac in layers.The sac was isolated and separated from the surrounding structures. The sac opened and the contents were returned to the abdominal cavity. If the sac was found to be excessively redundant, it was excised and closed with Vicryl 2.0 (polyglactin 910). The midline fascial defect closed with 1.0 prolene (polypropylene). The space created over the rectus sheath all around by combination of blunt and sharp dissection to fit in the mesh size of atleast 7x 5 cms centering the defect. A polypropylene mesh (prolene mesh, Johnson and Johnson) of size 7 x5 inches placed centering the defect and anchored to the rectus sheath with polypropylene 2.0 (Figure 1). A suction drain was placed over the mesh and the subcutaneous tissue and the skin were closed in layers. Finally wound dressings applied.

Sublay technique

The steps leading up to dealing the sac are essentially the same.Now the plane must be formed between the rectus muscle and the posterior rectus sheath. The medial edge of the rectus abdominus was incised, and created a plane between the rectus muscle and the posterior rectus sheath on each side. The space to accommodate the mesh size of approximately 7x5 inches was created all around the defect. A 7x5-inch polypropylene mesh (prolene) was placed centering the defect. The mesh is anchored to the posterior rectus sheath (Figure 1). A vaccum suction drain was placed over the mesh. The linea alba was closed with polypropylene no.1 and the subcutaneous tissue and skin were closed in layers.

Post-operative care and follow-up

All subjects received standard post-operative care, which included analgesics as needed and three doses of intravenous broad-spectrum antibiotics followed by oral antibiotics for next three to five days. Drain output was monitored and the drain removed when it fell below 20 milliliter for 24 hours. On the third postoperative day, wounds were inspected and classified as clean, infected, or wound collections. In cases of wound infection, the discharge was sent for culture and sensitivity. A syringe was used to aspirate wound collections (seromas), which were then sent for culture and sensitivity. Aspirations continued on a daily basis until there was no more collection was evident. Regular wound dressings were carried out until the wound was completely healed. Reports of culture and sensitivity were documented and managed appropriately. Subjects were seen in the outpatient clinic on the seventh to tenth postoperative day for suture removal. Further follow-ups were recommended after three months, six months, and a year. In this new facility, outpatient records are not kept in the medical records room. Instead, they are carried with the patients. Given that the phone numbers are in the inpatient files, we made the decision to conduct a telephone follow-up. Upon verifying the patient's identity, questions about any issues they had with the PUH procedure were asked. Subjects were specifically asked about any pain or swelling at the surgical site. If they claim to have no issues with the procedure, it is presumed that there is no recurrence. However, if they have any pain or swelling at the operated site, they will be called to the outpatient clinic for clinical examination on a designated day.

Statistical analysis

The data was entered and analyzed using IBM SPSS statistics version 22.0.The chi-square test was performed and p value of less than 0.05 was considered as significant.

The study included 35 subjects in each arm who met the inclusion and exclusion criteria.The average age was 30-40 years, with 14 (40%) in the onlay group and 15 (42.5%) in the sublay group belong to this age group. Females outnumbered males in both groups, with 18 (51.4%) in the onlay group and 20 (57.1%) in the sublay group (Table 1).

Table1. Age & gender distribution

Diabetes mellitus was the most prevalent co-morbidity in both groups, followed by hypertension and obesity (Table 2).

Table 2. Comorbidities

Surgical site infections occurred in 4 cases (11.4%) in the onlay group and 2 cases (5.7%) in the sublay group. Seroma formation occurred in 3 cases (8.6%) in the onlay group and 2 cases (5.7%) in the sublay group (Table 3).

Table 3. Post-operative complication and recurrences in both groups

The follow-up period ranged from 6 to 13 months, with the average period being 7.3 months for onlay group. For sublay group the average follow-up was 6.8 months with range of 6 to 12 months. The onlay group's operating time ranged from 40 to 70 minutes (SD 10 minutes), with an average of 45 minutes. It was 75 minutes in the sublay group, with a range of 50 to 90 minutes (SD 12 minutes) (Table 4).

Table 4. Duration of surgery and follow up in both groups

Figure 1. Various places of mesh placement areas

In this study, we evaluated the statistical significance of onlay and sublay repairs for PUH. Though comparing post-operative complications, recurrences, and operative time was the main focus of our study, we briefly discussed demographic aspects of PUH as well.The age range of 31 to 40 years old is where PUH is most frequent in our series with 14 subjects (40%) in the onlay group and 15 subjects (42.5%) in the sublay group belong to this age group.  It is prevalent in women. Women made up 57% of the sublay group and 51.4 % of the onlay group. Diabetes mellitus was the most prevalent co-morbidity in both groups, followed by hypertension and obesity.Our study's demographic findings align with the observations currently available in the literature. For example, a retrospective study by Mohammad Za et al. and a prospective study by Shankar et al. both support the age incidence and female preponderance.⁶

We also analyzed the frequency of superficial wound infections (SSIs) and the seroma formation, the two most common immediate post-operative complications after PUH surgery.There were four instances of SSI in the onlay group and just two in the sublay group (P-value 0.803).  Seroma formation was noted in 3 cases of onlay group and 2 cases of sublay group equating with 8.57 and 5.71 percent and p value being 0.657.The recurrence rate is the most important consideration in any hernia surgery, and it was evaluated next. No recurrence was observed during the follow-up period in either group. The follow-up period ranged from 6 to 13 months with the average being 7.3 months. It is not surprising that we found no recurrence during this short-term follow-up period. Panguluri ASNM et al conducted a prospective research with 30 patients in each arm and found no recurrence during the six-month follow-up period.⁷ In a prospective study by Rizig Heneta et al which had 16 patients in each arm also noted no recurrence in neither arm during the study follow-up period of six months. In another study done by Jayesh Bodana et al which was again a prospective study which had 10 patients in each arm, noted recurrence of one case in each technique with insignificant p value (0.092).⁸

On the contrary, other research has found that the sublay group has lower recurrence rates than the onlay group. In a recent study on this subject, Yassen Babar et al. (2024) reported a randomized prospective study with 60 patients in each arm, pooling patients from various surgical centers. They found that the onlay group had recurrence in 12 subjects (20 percent) and the sublay group had recurrence in four subjects (6.7 percent), with a significant p value of 0.03.⁹ Qamar Ahmad et al. (2019) conducted a prospective trial with 50 patients in each arm and a mean follow-up of 15 months. They found that three patients (6%) in the onlay group experienced recurrence, but no recurrence was seen after sublay mesh repair (p=0.079).¹⁰The most comprehensive study on this subject was conducted by Gyogy Weber et al, who included 953 patients in a five-year follow-up period and carried out a five-year randomized, multicentric study on the surgical treatment of PUH. Of the two groups in the study, one group of 494 individuals had a smaller hernia (defect size 5- 25 cms²), whereas the other group with 459 patients had a bigger hernia (defect size greater than 25 cm²). With the p value less than 0.05, they concluded that onlay mesh repair led to lower recurrence rates of 12 percent (n=22) in the big hernia group than sublay repairs, which had recurrence rate of 20 percent (n=38).¹¹

An additional variable that was examined was the average operating time. The onlay group's duration was 45 minutes, with a range of 40 to 70 minutes (SD 13 minutes). The sublay group's duration was 75 minutes, with a range of 50 to 90 minutes (SD 12 minutes). In their research, Karam Singh and associates noted that the onlay group's average operating duration was 58.12 minutes, whereas the sublay groups' average working time was 82.56 minutes. According to several other research studies, onlay repairs take less time than sublay repairs. Due to the time required to dissect and create a space in the retro rectus region, sublay repair takes longer time.¹²

Post-operative complications and recurrence rates are the most important considerations when selecting a surgical technique. The post- operative wound complications in our study were slightly more in onlay repairs. A small increase in wound-related complications following onlay repairs is statistically insignificant. During the follow-up period neither of the study's arms experienced any recurrences. In our investigation, the follow-up period was brief. According to certain research in the literature, onlay repairs have a higher recurrence rate than sublay repairs. Interestingly, a number of studies have not found a statistically significant increase in recurrence in onlay repair groups.

In this study, the onlay group has a marginally higher incidence of SSI’s and seroma formations, albeit this difference is not statistically significant. The onlay group's operating time is significantly shorter. Both the techniques had no recurrence at least in the short term follow-up. This is assuring for the onlay technique where there is a concern regarding the recurrence. Even though neither group experienced recurrence, long-term follow-ups are required before any inferences can be drawn about the long term recurrence rates. To determine the actual recurrence rates in the long term and reach a conclusion regarding the superiority of one technique over another, a randomized trial with a larger sample size and a longer follow-up period is required. As a result, we conclude that the technique choice is currently better suited to each patient's requirements. The resources offered by the specific center as well as the surgeon's preferences must be taken into account.

Limitations

Among the study's shortcomings are its retrospective design and its reliance on case file documentation for data. It's possible that there were errors and incomplete documentation. Follow-up was conducted over the phone and depended on the patient's comprehension of recurrence. It would have been preferable to have physical follow ups. The follow-up period was also on shorter side.

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