Imaging changes after recent inguinal hernioplasty: normal or abnormal ?

Clinical History

A man presented 48 hours after a right open-mesh inguinal hernioplasty, complaining of mild wound bleeding despite compressive medications. Medical history included hypertension, psychiatric illness, resected T2N0M0 colon adenocarcinoma, anticoagulation due to previous thromboembolism (International Normalized Ratio 3.1).
Physical examination confirmed a swollen groin, tender ecchymosis along the ipsilateral spermatic cord and scrotum.

Imaging Findings

Ultrasound (Fig.1) showed normal-appearing testicles, thickened inhomogeneous extrainguinal spermatic cord with fluid-like portions, without inflammatory hypervascularization. An inhomogeneous, partly anechoic collection was noted behind the rectus abdominis muscle.
Concern for haemorrhage led to urgent multidetector CT (Fig.2), including reconstruction of oblique-coronal images tilted parallel to the extrainguinal spermatic cord. CT showed moderate postsurgical abdominal wall air, swelling of the operated groin with oedematous fat stranding, non-haemorrhagic fluid along the extrainguinal spermatic cord. Active bleeding was excluded. Additionally, a 3.5-cm well-demarcated nonenhancing mass-like structure with solid periphery and internal fatty attenuation was noted in the right iliac fossa, abutting the internal inguinal ring and corresponding to the sonographic finding in Fig.1c. Separation from external iliac vessels by a fat plane and correlation with surgical details led to diagnose expected postoperative appearances including mesh plug positioning.
During the uneventful subsequent clinical course, sonographic follow-up (not shown) confirmed regression of imaging changes.

Discussion

Worldwide, inguinal hernia repair (IHR) is arguably the most frequent general surgery procedure. During the last 25 years “tension-free” mesh hernioplasty became the standard technique, which may be performed through either an open or laparoscopic approach and resulted in significantly lower recurrences compared to traditional IHR. Alloplastic materials used in IHR include mesh patches, cup-like mesh plugs deployed into the inguinal canal, or a combination of both [1-4].
The postoperative course following mesh IHR is uneventful in the majority of patients, but occasional (<1%) intra- and early postoperative complications may develop, particularly in elderly patients with comorbidities and elevated anaesthesiological risk. The essentially clinical postoperative assessment is often hampered by thickened subcutaneous fat, local pain and wound tenderness. Variable degrees of groin swelling, mostly caused by impaired venous flow and post-surgical oedema, occur in almost one-third of patients and generally resolve over time. Due to the large number of IHR procedures and to fear of litigation, radiologists are increasingly requested to investigate suspected iatrogenic complications [5, 6].
Colour Doppler ultrasound may helpfully detect fluid seromas, variable-echogenicity hematomas, hydrocele, signs of testicular ischemia or epididymo-orchitis. However, hypoechoic swelling around the mesh is challenging to interpret [5, 6]. Conversely, multidetector CT including multiplanar study review comprehensively depicts the postoperative anatomy and abnormalities involving the inguinal canal and spermatic cord, and consistently provides crucial information for triage of complications such as bleeding or abscess. Interpretation requires familiarity with expected postoperative CT appearances, including spermatic cord thickening secondary to surgical manipulation, inhomogeneity of anterior pelvic wall and subcutaneous tissues at the operated inguinal region. The thin linear polypropylene meshes are isoattenuating to muscles and identifiable in only 20% of patients. Furthermore, as this case exemplifies focal pseudolesions (FPLs) nearby the anterior pelvic wall are commonly observed after IHR. These well-demarcated round-, ring- or ovoid-shaped structures occur in 40-80% of patients treated with mesh plugs, generally measure 2.5 cm (range 1.3-3.9 cm) in size with variable attenuation (partly adipose in two-thirds of cases), and correspond to the plug plus trapped fluid, blood or fibrous tissue. Similar, smaller appearances are encountered in up to 24% of patients after flat mesh IHR. Since FPL do not represent complications and do not require treatment, radiologists should be aware of the recent surgery to avoid misinterpretation (see differential diagnosis Table, Fig.3). Imaging follow-up is unnecessary when characteristic CT findings are favourable without clinical-laboratory signs of infection and blood loss [7-9].

Differential Diagnosis List

Final Diagnosis

Normal postoperative appearances after open mesh inguinal hernioplasty.

URL:	https://www.eurorad.org/case/13123
DOI:	10.1594/EURORAD/CASE.13123
ISSN:	1563-4086