The abdominal wall extends from the diaphragm to the pelvis, encompassing the largest cavity within the body. Ruptures of the body wall most frequently occur as a result of blunt force trauma and are classified according to their location: paracostal, lateral, prepubic, ventral, inguinal and femoral (Smeak, 2018). For this article, we will focus on the diagnosis and management of prepubic tendon rupture.
In dogs, the prepubic tendon comprises fibres of the rectus abdominus and internal and external oblique muscles, which form the ventral abdominal wall. In cats, no true tendon exists. Instead, the tendon of the pectineus muscle attaches to the ileopubic eminence and the crura of the superficial inguinal ring inserts onto the cranial border of the pubis on either side of the eminence (Constantinescu et al., 2007).
Causes and consequences of rupture of the prepubic tendon
Road traffic accidents account for the majority of prepubic tendon rupture cases (Beittenmiller et al., 2009). Given the traumatic nature of this presentation, concurrent injuries are common; in particular, orthopaedic injuries such as pelvic fractures are commonly seen. Any organ in the area of the defect is at risk of herniating; this commonly includes the bladder, colon or uterus, or long, mobile structures such as the small intestine and omentum.
Clinical signs
Patients with acute presentations may show signs of shock or respiratory distress and are frequently in significant pain. Emergency stabilisation measures should, therefore, be undertaken prior to further investigation.
Patients with acute presentations may show signs of shock or respiratory distress and are frequently in significant pain
Dysuria associated with herniation of the bladder, as well as swelling and bruising over the caudoventral abdomen and inguinal region, may raise suspicion of damage to the body wall. However, clinical signs associated with prepubic tendon rupture may not be immediately apparent and can progress over time.
Diagnosis
Diagnosis involves a combination of palpation and imaging. The removal of fur over the ventral abdomen may help reveal abdominal asymmetry as well as bruising, which can be extensive. Swellings may be fully or partially reducible.
Radiography can be used to identify disruption to the body wall and herniated abdominal organs (Figure 1) and assess concurrent orthopaedic injuries. Ultrasonography of the area may help identify herniated abdominal contents, such as the bladder or intestines.
Where available, computed tomography (CT) is frequently employed due to the polytraumatic nature of presentation; however, diagnosis can usually be achieved without the need for advanced imaging.
Initial management
Treatment must prioritise the stabilisation of the patient – the exact nature of this will depend on the patient’s presentation. Opioid-based analgesia, intravenous fluid therapy and oxygen supplementation are commonly required. If the bladder is herniated or if there is a suspicion of bladder rupture, an indwelling urinary catheter is indicated until the patient is stable enough to undergo a prolonged anaesthetic.
If the bladder is herniated or if there is a suspicion of bladder rupture, an indwelling urinary catheter is indicated until the patient is stable enough to undergo a prolonged anaesthetic
Timing of surgery
Surgery should wait until the patient has been fully stabilised. While there is some debate in the literature regarding the optimal timing of surgery, most prepubic tendon ruptures result in large defects and are at low risk of strangulating entrapped organs. Surgery may, therefore, be delayed to give the bruising and swelling of damaged muscles time to resolve (Peterson et al., 2015).
Most prepubic tendon ruptures result in large defects and are at low risk of strangulating entrapped organs
Immediate surgical exploration is indicated where strangulation of abdominal viscera is identified or in cases where there is a suspicion of gastrointestinal rupture, such as the presence of free abdominal gas on imaging.
Surgical principles and approach
Position the patient in dorsal recumbency with the hindlimbs relaxed. Catheterisation of the urethra before surgery can help with intraoperative identification, thus avoiding accidental entrapment during closure of the defects. A wide clipped area should also be prepared.
A midline approach is made to the abdomen and full abdominal exploration is performed to assess for concurrent injuries. Necrotic tissue should be debrided and injuries to other organs managed appropriately (eg resection of perforated or devitalised intestine). The exact location of the rupture should then be identified and herniated tissue returned to its normal anatomical location (Figure 2).
Wherever possible, it is preferable to use the patient’s own tissue for repair over synthetics such as mesh, as these materials increase the risk of surgical site infections (Beittenmiller et al., 2009). The defect should be closed anatomically and without tension. While cruciate or mattress sutures will help distribute tension, larger defects may be challenging to close, in which case muscle flaps, such as the rectus abdominus flap, are most frequently employed to cover the deficit (Smeak, 2018).
Sutures of polydioxanone, monofilament nylon or polypropylene should be placed in strong tissues, such as the tendons or fascia, ensuring adequate bites are taken. Preplacing sutures allows for good visualisation during suture placement to avoid incorporating vital abdominal structures (Figure 3). Deeper sutures are then tied first.
In cats and small dogs, sutures can be placed through the obturator foramen, ensuring no soft tissue is caught between the suture and the bone as this can lead to premature loosening of the repair. In larger patients, it is advisable to drill holes in the pubic brim to create an anchor point for suturing the remnants of the prepubic tendon and the ruptured caudoventral abdominal muscle to the pubis.
Closure
Close any concurrent tear that passes through the inguinal ring/inguinal ligament. If the rupture extends into the femoral region, anchor the abdominal muscle aponeuroses to the fascia of the medial femoral area. Care must be taken to avoid entrapment of the neurovascular structures. Once the herniorrhaphy has been completed, abdominal closure should be routine.
Post-operative care
Adequate analgesia should be provided throughout the post-operative and convalescent period. Initially, this will likely involve opioids, such as methadone and buprenorphine, along with non-steroidal anti-inflammatories and/or gabapentin. Paracetamol should also be provided for canine patients for a period of 10 to 14 days as needed. Strict cage rest will be required for a period of four to six weeks. Additionally, it is essential to avoid self-trauma of the surgical site and increased intra-abdominal pressure that may be caused by anxiety or exertion. Canine patients must be confined to a lead when out of the crate for toileting.
Prognosis and complications
Prognosis is generally determined by concurrent injuries, but mortality in cases of prepubic tendon rupture is reported to be low.
Strict adherence to post-operative exercise restriction and judicious avoidance of tension during herniorrhaphy should limit the risk of post-operative complications
Along with routine surgical complications such as wound breakdown and infection, skin sloughing and accidental entrapment of the urethra during suture placement are reported. Owners and practitioners should also be aware that there is an approximately 15 percent risk of failure of the herniorrhaphy, which can occur within the first month following repair (Smeak, 2014). Strict adherence to post-operative exercise restriction and judicious avoidance of tension during herniorrhaphy should limit the risk of post-operative complications.
Key takeaways
- Traumatic body wall ruptures may not be apparent on presentation
- Concurrent injuries are common and may need to be addressed first
- Full abdominal exploration is always required
- Specific techniques, such as muscle flaps, may be required for tension-free closure
- Preplace interrupted tension-relieving sutures when performing a herniorrhaphy
