Mind the gap: imaging spectrum of abdominal ventral hernia repair complications

Awareness of the type of hernia repair and interaction with the surgeon is important for better understanding of the postoperative field and hence useful reporting contributions. Commonly used investigations are ultrasonography (USG) and CT [7]. Radiographs are used in suspected cases of small bowel obstruction or perforation (Fig. 1). CT aids in characterization of complications especially with use of contrast (oral -positive/ neutral, intravenous) that gives details about collections and bowel involvement. Various types of mesh are used in current practice with differences in composite material and structure (Fig. 2). Polypropelene or polyester mesh are preferred for extraperitoneal placement due to light weight and large pores hence lower infection risk. Mesh that is used for laparoscopic repair generally have a protective membrane or film to reduce adhesions with intraperitoneal structures [5, 8]. The major factors that determine mesh visibility on CT are density, structure (woven or knitted), and thickness. Polypropylene, polyester-based mesh is isodense to muscle and hence not visualized unless with a fat interface or metallic tackers. Polytetrafluoroethylene (PTFE) based are hyperdense and are readily seen (Fig. 3). Composite mesh made with different layers is visible on CT if composed of PTFE and again depends on the thickness used.

Ultrasound also shows variable appearance [9, 10] (Fig. 4) and presence of fluid around generally enhances its echogenicity and plays an important role in diagnosing mesh migration and infection. The study and modality selection hence must be tailored according to the clinical presentation with an ability to complement with an additional modality.

Nontubercular Mycobacterium are resistant rapidly growing mycobacterium including common species such as Mycobacterium chelonae, Mycobacterium goodie, Mycobacterium fortuitum, and Mycobacterium abscesses. They have predilection for implants and are reported with hernia mesh, breast implants, and orthopedic prosthesis. Contamination occurs through inadequate high grade sterilization of instruments, rinsing with tap water and using partially dried instruments. These organisms have affinity for dermis and subcutaneous tissue and typically present at 3–4 weeks’ post-surgery appearing as an erythematous nodule followed by sinus formation [13].

The non-healing sinus does not respond to routine antibiotics and is negative on aerobic/anaerobic cultures (Fig. 8). The clinical symptoms such as fever are absent. Imaging reveals sinus tracks with focal collections. No specific imaging feature of NTM infection is described. High clinical suspicion is needed based on above described presentation. Hospital outbreaks with atypical mycobacteria have been reported and are attributed to usage of common water reservoir harboring the pathogen [14]. Varying antibiotic combinations are used for treatment with most cases requiring mesh removal [15].

Direct organ injury: urinary bladder injuries are reported with laparoscopic inguinal repairs [12]. Bowel perforation is very rare and can lead to fistula, sepsis, and has increased mortality.

Infertility: injury to the vas deferens and testis at the time of surgery is ~ 0.3% for adults, 0.8–2.0% for children, and 0.5% of primary hernia repairs respectively [24]. Recurrent hernia repairs have higher rates of infertility. These are long-term complication and imaging is not used for diagnosis.

Post inguinal hernia surgery chronic pain: chronic groin pain is seen in up to 13–20% of individuals undergoing inguinal hernia repair [25]. Pain can be secondary to nerve damage intraoperatively or damage postoperatively due to neuroma formation, irritation by mesh margins, or by fibrotic reaction [25]. Use of laparoscopic techniques and light-weighted mesh have shown to reduce the incidence of chronic pain. In general, non-usage of sutures or tackers have shown to produce less pain as it provides a tension free repair. The nerves that are implicated include ilioinguinal, iliohypogastric, genital, or femoral branch of genitofemoral nerve and rarely lateral femoral cutaneous nerve. Chronic pain is usually dragging in nature, can be debilitating, and impede quality of life. Various management options ranging from pain medications to surgical neurectomy are undertaken. Imaging plays a role in providing guided ilioinguinal and iliohypogastric nerve injections/ablations [26]. Both CT and USG are used for localization, though the latter is commonly used (Fig. 16).