Frequency of Abdominal Wall Hernias: A Nigerian Hospital Experience

Introduction: Hernia is a very common condition in all populations, and its surgical operation constitutes a major workload for physicians worldwide. Although great numbers of these procedures are done in primary and secondary care settings as well as in private hospitals and as part of surgical missions to rural areas, a significant proportion is still present in tertiary centers.

Aim: To review the pattern of external hernias operated upon in Federal Medical Centre, Owerri, over a 10-year period.

Methods: The theatre records were searched for all patients who underwent surgical operations for hernia in the period of 2005–2014. The data on patient demographics, indication for surgery, and procedure performed were retrieved.

Results: A total of 902 patients underwent operations for different types of external hernias. The overall male/female ratio was 2.6:1. Operations for inguinal hernia were the most common, accounting for 72.9% (658) of the total. Ventral hernias constituted 25.1% (n=227) of the cases whereas 1.5% (n = 12) of patients had femoral hernia. One hundred and twelve patients (12.4%) had emergency surgery, of which 78 were for inguinal hernia. Mesh repair was started in 2009 and was utilized in 72 (8%) cases. Laparoscopic method of repair was used in only two patients.

Conclusion: The pattern of operation for hernia in our center mirrors the experience in other local centers. Modern methods of repair are gaining ground.

Introduction

External abdominal wall hernias constitute an enduring healthcare burden all over the world. There are variations in the prevalence in different countries but limited data suggest a higher hernia prevalence in Africa compared to Europe and North America [1]. Globally, over 20 million hernia operations are estimated to be done annually [2]. Moreover, more recent estimates from the Global Burden of Disease Study suggest a global annual mortality of 44,200 in addition to disability-adjusted life years (DALY) rate of 43.5 per 100,000 [3], [4]. A large portion of this burden is attributed to low-middle-income countries where the high prevalence of hernias does not translate to a correspondingly large volume of these hernias being operated upon. The inguinal hernia repair rates across studies from Australia, USA, and England has been decreasing over the years but it is estimated at 194–217 operations per 100,000 [5]–[7]. The inguinal hernia operation rate in an Eastern African population has been estimated at 25/100,000 as against an expected 175/100,00 [2]. A population-based study in Ghana arrived at 65 overall hernia repairs per 100,000 [8]. Inguinal hernia is the most common type of external abdominal wall hernia. However the report on the relative frequencies of the various types of hernia varies among several reports [2]. We aim to contribute to the body of knowledge in this regard from our experience.

Methodology

This was a descriptive retrospective study conducted at Federal Medical Centre, Owerri, Nigeria. The theatre records were searched for all patients who underwent hernia operation over a 10-year period from January 2005 to December 2014. The data retrieved included patient demographics, indication for surgery, and type of surgery performed. Data analysis was done with IBM SPSS version 23.

Results

A total of 902 patients underwent operations for different types of external hernias, within the 10-year study period. Within the study period 7,902 operations were done in general and paediatric surgery units. The overall male/female ratio was 2.6:1. Operations for inguinal hernia were the most common, accounting for 72.9% (658) of the total (Table I). Ventral hernias constituted 25.1% (n = 227) of the cases whereas 1.5% (n = 12) of patients had femoral hernia. One hundred and twelve patients (12.4%) had emergency surgery, of which 78 were for inguinal hernia (Table II). Mesh repair was started in 2009 and was utilized in 72 (8%) cases. Laparoscopic method of repair was used in only two patients.

Table I. Distribution of Abdominal Wall Hernias

Hernia type	No	Percentage
Inguinal	658	72.9
Umbilical	89	9.9
Incisional	63	7.0
Epigastric	45	5.0
Paraumbilical	30	3.3
Femoral	12	1.3
Others	5	0.6
Total	902	100

Table II. Summary Data of Hernia Operations

Inguinal hernia
Male (582):female (76) = 7.7:1
Right:left = 1.9:1
Bilateral = 47 (7%)
Emergency operations = 78 (11.9%)
Femoral hernia
Females 10/males 2
Emergency operations = 2
Incisional hernia-females 55:males 8

Discussion

The incidence of abdominal wall hernia is not precisely known, however, it occurs in about 1.7% of the population. Inguinal hernia account for 75% of these hernias [9]. The order of frequency of the various hernias have undergone changes over the past few decades. Classic decreasing order frequency from surgery textbooks used to be in the following format: inguinal, femoral, umbilical and other hernias [10]. However, a United Kingdom series covering three decade showed the following relative order of frequency: inguinal, umbilical, epigastric incisional, paraumbilical, femoral and other rarer hernia types like spigelian hernia [2]. Our results revealed a somewhat similar sequence: inguinal, umbilical, incisional, epigastric, paraumbilical, femoral and others. This compares to the pattern from a study carried out in Cameroon [11]. Inguinal hernias accounted for 72.9% of all our hernia operations which is comparable to the 75% mentioned in several series, but still lower than the 86.3% mentioned in the same study from Cameroon. The inguinal hernia right to left ratio of 1.9:1 compares favourably to the 2:1 seen in other published literature [12], [13]. Our results show that 11.9% of these operations were done on emergent basis. In developed countries the proportion of emergent groin hernia repair ranges from 2.5% to 7.7%, [14] whereas a study done in Tanzania showed a value of 38.5% [15].

Incisional hernia repair came third in our study. While this tallies with the findings from Zaria, incisional hernia was the second most common grouping from the work in Ibadan and Cameroon [11], [16], [17]. Abur et al. rationalized that the numbers for incisional hernia may have been higher because of the higher literacy rate in the Ibadan metropolis, which may lead to an increased tendency to accept surgery. It is however salient to note that our series included paediatric patients, who accounted for 30.3% of study population, a figure not too dissimilar to the 21.9% seen in a Ghanaian study [13]. This may be part of the reasons why umbilical hernia came second in our study.

The increasing number of laparotomies particularly gynecologic and obstetric operations in females is driving the prominence of incisional hernias. Olasehinde and colleagues noted that incisional hernia accounted for 27% of hernias in females, being second only to inguinal hernia [18]. While overall 7% of our patients had incisional hernia, interestingly 87.3% (55/63) of these were females. Conversely in a Ghanaian study there were almost as many incisional hernias in females (52.9%) as in males (47.1%) [13]. These variations could be a reflection of the quality of obstetric surgical practice in the respective environments.

Femoral hernia ranked a distant 6^th in the hierarchy of contribution to the hernia burden to 1.3% (12/902) of the cases. This is consistent with other reports from Zaria, Ibadan and Cameroon where it ranked 5^th [11], [16], [17]. This still reinforces the observation that femoral hernia is not the second most common type of abdominal wall hernia as stated in some surgical textbooks [2], [10].

The period of study was over a time when tissue repair of hernia was the default mode of operation. Polypropylene mesh repair was started midway through the study period in 2009, and thus only 8% (72/902) of patients benefited from the procedure. In fact, in low-resource settings medical officers can be trained to perform elective inguinal hernia repair with mesh with comparable outcomes to surgeons [19]. Repair with mesh has become the standard in our hospital and further studies will reflect that. We also had commenced laparoscopic hernia surgery; and within this study period two cases of transabdominal preperitoneal (TAPP) inguinal hernia repair were done successfully. Over the course of 15, there was an increasing use of laparoscopic approaches for inguinal hernia repair from 14% to 38.9% in a population in Australia [5].

Being a hospital-based study, a limitation is that the frequency data may not be generalizable to the wider population. It does not capture the population that chose not to come to the hospital and those who may not be fit for operation. Therefore, a population-based study needs to be performed.

In conclusion, the frequency pattern of abdominal wall hernia may be undergoing a change, as seen in other centres in Nigeria. While inguinal hernia still account for about three-quarters of all hernias, incisional hernia has become more prominent while femoral hernia is not as prevalent as has been taught in the past.