Abstract

Background: Aim: incisional hernias occur through a weakness at the site of abdominal wall closure after surgery and is a common condition encountered in day to day surgical practice. It lends itself to multiple and varied aetiological factors. Despite recent advances in the management of incisional hernias, the recurrence rate is still high. Incisional hernia is uncommon in pregnancy, however when it occurs serious and life-threatening complications may arise. Thus there is a need to revisit the possible aetiological factors that may give rise to incisional hernia in our locality so as to prevent them. To our knowledge no such study has ever been undertaking here. Materials and methods This is a five-year retrospective survey conducted at the antenatal clinic of the university of Port Harcourt Teaching hospital in southern Nigeria between January 2008 to December 2013. A total of one hundred and seven patients with incisional hernia were identified and some aetiological factors for incisional hernia in the patient were deciphered. Each patient’s abdomen was examined to confirm the presence of incisional hernia, and type of surgical incision used. All these were collated and analysed. Results: Obesity was the commonest risk factor 78 (72.9%), while wound sepsis accounted for 61 (57.0%) Nearly all patients had longitudinal incisions 105 (98.1%) while for some 11 (10.3%), there were no identifiable risk factors. Also, Caesarean section accounted for majority of the surgeries that led to incisional hernia in the study population 72(67.3%) followed by myomectomy. Emergency surgeries were complicated by incisional hernia than elective Conclusion: This study found that the commonest aetiological factors for incisional hernia in our locality but not limited to: Obesity, wound sepsis, emergency surgeries as well as longitudinal incisions. Interestingly these are all modifiable risk factors and are amenable to health education and sound surgical techniques.

1. Introduction

An Incisional hernia exists when there is a protrusion of an intra-abdominal viscus, through an anterior abdominal wall fascial defect following an abdominal surgical incision. ¹ in Europe the term “ventral hernia” is used synonymously with incisional hernia while in USA, ventral hernia is used to describe all abdominal wall hernia, other than groin hernias ².

Incisional hernia is a common surgical condition encountered in day to day practice. The reported incidence of incisional hernia after midline laparotomy varies widely ranging from 3-22% and becomes doubled if the wound gets infected ^{3, 4}. Usually 50% of incisional hernias are detected within 1 year of surgery, but they can occur several years after surgery, with a subsequent risk of 2% per year ⁵. Consequently, incisional hernia repair is a common procedure with about 350,000 repairs performed annually in the United States ⁶.

Patient-specific risk factors for postoperative ventral hernia include advanced age, malnutrition, presence of ascites, corticosteroid use, diabetes mellitus, cigarette smoking, wound infection, wound dehiscence emergency surgery and obesity. ^{7, 8, 9, 10, 11} Other factors include use of vertical abdominal incisions, recurrent incisions and previous laparotomy, post abdominal wound dehiscence and a low preoperative haematocrit ^{12, 13}.

Patients with some connective tissue diseases (Marfan’s syndrome, osteogenesis imperfecta, and Ehlers-Danlos syndrome) have increased incidence of incisional hernia ^{14, 15}.

Usually the diagnosis is clinical and ultrasound, CT scan and MRI are only required in situations where the diagnosis is not clear. Treatment strategy is dependent on whether it is elective or emergency presentation. Operative treatment is done for complicated cases while elective cases throws up a variety of therapeutic options.

A conservative approach, including manual reduction and use of an abdominal binders, trusses and corsets during the antenatal period and labour, has been applied with varying success ^{16, 17, 18, 19} These nonsurgical management options are considered to be ineffective. Nevertheless, these may be the only options in a patient who is not a reasonable risk for surgery ^{20, 21, 22}.

Surgery remains the only viable therapeutic option, and techniques of repair has progressed from simple herniorrhaphy to hernioplasty currently. Tension free mesh repairs are now considered the gold standard of surgical care. Surgical techniques continue to improve with the advent of Laparoscopic and robotic approaches in the management of this pathology. Mesh repair has decreased the high recurrence rate historically associated with primary suture repair to less than 25%. ^{23, 24, 25} However, mesh related problems such as wound complications, discomfort, pain and a potential loss of elasticity of the abdominal wall raise the question whether all patients should have mesh repair ^{26, 27}.

There is no consensus on the management of hernia in pregnant women because previous study samples are small and experience in hospitals is limited. Pregnancy after repair of a hernia with mesh is safe and there is no increased risk of relapse ²⁸. In the absence of emergency indications, conservative management is preferred. ²⁹. Interestingly simultaneous repair and caesarean delivery have been reported with those with elective indications even though this is still controversial ^{30, 31, 32}.

This study was done to highlight the existence of a etiological factors in the causation of incisional hernia in pregnancy thus sensitizing us to these challenges with the hope of mitigating them.

2. Materials and Methods

This is a five-year retrospective survey conducted at the antenatal clinic of the university of Port Harcourt Teaching hospital in southern Nigeria between January 2008 to December 2013.

Prospective cases were identified at the antenatal clinics of the institution by the research team, consisting of a General surgeon, a plastic surgeon and 3 research assistants.

The University of Port Harcourt Teaching Hospital is a five hundred bed tertiary care health facility located in the south-southern part of Nigeria. It sees an average of two hundred thousand (200,000) patients annually with about two thousand (2,000) antenatal clinic attendance yearly.

Any antenatal clinic attendee with any circumscribed abdominal swelling around a previous surgical scar was referred to members of the team for further scrutiny and if confirmed to be an incisional hernia was enlisted into the study after obtaining due consent.

A research proforma was used to extract relevant data from the patient, and/ or the case records if the index surgery was done at the facility.

Data extracted include patient’s age, occupation, elective or emergency nature of the surgery and type of surgery, history suggestive of known risk factors like postoperative wound sepsis, dehiscence, wound re-suture and previous multiple laparotomies were sought and recorded. The abdomen was examined to confirm the presence of incisional hernia, and type of surgical incision used.

The patient ‘s height was measured and her prenatal weight ascertained. The data were analysed using SPSS version 22.

All antenatal clinic attendees with the above features

Patients whose index surgery was done outside our domain and are unable to provide reliable and sufficient information for us to make reasonable conclusions were excluded.

3. Results

A total of one hundred and seven patients who met the inclusion criteria and consented to participate in the study were recruited. Their ages range from 20 to 49 years, and more than half were within the (30 to 39) year age bracket Table 1. All the patients, understandably were in the reproductive age group (15-49 years).

Obesity was the commonest risk factor 78 (72.9%), while wound sepsis accounted for 61 (57.0%) Nearly all patients had longitudinal incisions 105 (98.1%) while for some 11 (10.3%), no aetiological factors were deciphered Table 2.

Caesarean section accounted for majority of the surgeries that led to incisional hernia in the study population 72 (67.3%) followed by myomectomy as shown in Table 3.

Emergency surgeries 68 (63.3%) accounted for more of the previous surgeries done than elective Table 4.

4. Discussion

One hundred and seven patients with incisional hernias attending antenatal clinic at the institution were studied, as will be expected they were all within the reproductive age group and it has been reported that approximately every tenth patient undergoing incisional hernia repair is a woman of childbearing age. ³³ This age group are the ones subjected to prolonged or repeated pregnancy and labour involving stretching and weakness of the abdominal musculature and the ones most likely to undergo surgeries. Thus incisional hernia is more prevalent in this group. ³⁴

The risk factors encountered in our study population include obesity, wound sepsis, vertical incisions, prolonged ileus, wound dehiscence, recurrent laparotomies, emergency surgeries, and in some cases no aetiological factors could be adduced. These findings have been replicated by other workers. ^{7, 8, 9, 10, 11}

Obesity was a risk factor for 78 (72.9%) of our patients, Ahmed Alenazi et al ³⁵ reported 51.9% of their cases as obese. The slightly lower figure in their series may be due to the fact that he considered all anterior abdominal wall hernias not just incisional hernias. Other authors also found obesity a significant risk factor. ^{36, 37} Obesity affects incisional hernia indirectly by increasing the risk of wound infection and obesity related comorbid diseases (diabetes, atherosclerosis, etc.) as well as making abdominal closure technically more difficult.

Wound sepsis as an important risk factor as was also found in our study where 61(57%) had it in their index surgery. This has been replicated in other studies with one study reporting a figure as high as 79.5% ^{12, 34, 37, 38}. Wound infection predisposes to acute wound failure with postoperative separation of musculoaponeurotic layers and later incisional hernia if not promptly managed. All measures to prevent wound infection must be implemented even though these have not been helped by the constant mutations of the contaminating microbes and consequent development of antibiotic resistance. Wound dehiscence which usually follows wound sepsis was the risk factor in 19 (17.8%) cases as has been recorded by previous researchers. ¹²

Vertical midline incision was recorded in 78 (72.9%) cases. This type of incision is a known risk factor in incisional hernia formation. Studies have shown that transverse incisions are associated with a reduced incidence of incisional hernia compared to midline vertical laparotomies, although the data are far from conclusive ^{5, 10, 13, 37}. The least resistance to stress by intra-abdominal forces is offered by vertical incision, which transects the transversely oriented fascia fibers of the anterior abdominal wall, thus transverse incisions, like Pffanenstiel have lower incidence of incisional hernia.

Caesarean section accounted for 67 (62.6) of the surgeries that resulted in incisional hernias. This is the commonest surgery in women in the reproductive age group and accounted for the highest number of cases of incisional hernia ¹². This is followed by myomectomy another common surgery in women of this age group and General surgical operations then follow.

Emergency surgery is known to increase the risk of incisional hernia formation as has been found in our study (see Table 4) and also reported by other workers. Work done by Pollock in 1989, revealed that only 1.2% of the patients operated on elective basis had incisional hernia compared to 23.9% of the patients operated on emergency basis. ^{10, 39}

Increased intra abdominal pressure due either to ileus or adhesions does not enhance the healing of an abdominal scar, especially midline scar leading to increased incidence of incisional hernia. ³⁷ This was also evident from our study.

In eleven patients (11, 10,3%) no risk factor could be elicited, and hernia occurrence in these situations may be attributable to poor surgical techniques like overuse of diathermy, rough tissue handling, use of absorbable suture material, non-adherence to Jenkins rule and Smead Jones mass closure technique. ^{5, 40} Other factors that may account for this include presence of chronic cough, immunosuppression, hypoproteinaemia, and renal insufficiency. We did not include these risk factors in our study ab initio.

5. Conclusion

This study found that the commonest aetiological factors for incisional hernia in our locality include obesity, emergent surgeries, caesarean section operations, wound sepsis, longitudinal incisions.as well some occult factors. These are all modifiable risk factors, thus a reduction of the frequency of occurrence of incisional hernia and its complications in female patients can be achieved through a combination of health education and sound surgical techniques with good wound care. Other measures include a preference for transverse incision, and prophylactic use of mesh and antibiotics when indicated.

References