Evaluation of Four-Hand Reduction for Obturator Hernia with The Guidance of Sonography (FROGS) as a New Treatment Strategy for Obturator Hernia: A Retrospective Study

Obturator hernias are uncommon but are important causes of intestinal obstruction. Delayed treatment can be fatal. Emergency surgery is considered the most effective treatment; however, patients with obturator hernia usually have comorbidities, and this precludes them from emergency surgery. Previously, a few case studies reported successful manual reductions for an incarcerated obturator hernia. However, their ecacy was not statistically conrmed. We have devised a new manual reduction method for an incarcerated obturator hernia based on previous studies. We have named this method “Four-hand Reduction for Obturator hernia with the Guidance of Sonography” (FROGS). This study aimed to evaluate the effectiveness of FROGS as a new treatment strategy for obturator hernia. the after-FROGS the Manual was successfully in all 14 patients in the FROGS group, whereas in the before-FROGS group, 14 patients underwent manual reduction, of whom only one was successfully treated using the non-FROGS method. Bowel resection was avoided in all 14 patients in the after-FROGS group, whereas 8 patients underwent bowel resection in the before-FROGS group. There were no signicant differences in postoperative complications and mortality within 30 days after hernia presentation between the two groups.

Step 2 The assistant slightly rotates the hip joint laterally, thereby widely opening the hernia ori ce (Fig. 2).
Step 3 The assistant extends the hip and knee joints (Fig. 3).
To facilitate these movements, the assistant places one hand on the patient's upper thigh and the other on the patient's lower thigh. While the assistant performs the three-step maneuver, the surgeon keeps pushing the hernial sac. In Step 3, the surgeon pushes it even harder. The muscles along the obturator canal relax so that the hernial sac can be reduced. Two people continue this maneuver repeatedly until the hernial sac is completely pushed back. This movement may be reminiscent of a frog moving its legs while swimming, which is another reason the method is called "FROGS."

Statistical analyses
All statistical analyses were performed using R version 4.0.3 software (The R Project for Statistical Computing, Vienna, Austria). Continuous variables are expressed as mean ± standard deviation, and categorical variables are expressed as absolute numbers and percentages. All variables were analyzed using Student's t-test for continuous variables and the χ2 test or Fisher's exact test for categorical variables. A p-value of < 0.05 was considered statistically signi cant.

Results
A total of 37 patients with obturator hernias were admitted to the Department of Surgery at Kurashiki Central Hospital between April 2016 and September 2020. Before the FROGS technique was implemented, 23 patients had already been admitted (before-FROGS group). After November 2019, 14 patients were admitted, all of whom underwent FROGS as the rst treatment choice (after-FROGS group). The demographic characteristics of all patients are summarized in Table 1. All patients were females. All 37 patients were diagnosed with obturator hernia preoperatively by computed tomography. There were no signi cant differences in age, lesion side, duration of symptoms, diameter of the prolapsed bowel, and predisposing factors between the two groups. Body mass index was signi cantly lower in the after-FROGS group than in the before-FROGS group (p = 0.0158, Table 2).   Table 3).
Manual reduction was successfully performed in all 14 patients in the after-FROGS group (success rate of 100%). In the before-FROGS group, 14 patients underwent manual reduction, out of whom only one was successfully treated (success rate of 7.14%) using the non-FROGS method. The success rate of manual reduction was signi cantly higher in the after-FROGS group than in the before-FROGS group (p < 0.001, Table 2).
Of the 14 patients in the after-FROGS group, six underwent elective surgery. All six operations were performed using TAPP. Eight patients did not undergo elective surgery because of comorbidities. In the before-FROGS group, successful manual reduction was performed in only one patient who underwent elective surgery that was performed using TAPP repair. Emergency surgery could not be performed on one patient because of severe heart failure; this patient died at 6 days after admission. The other 21 patients underwent emergency surgery, including 17 patients who underwent laparotomy and 4 patients who underwent TAPP. The number of patients who underwent emergency surgery was signi cantly smaller in the after-FROGS group than in the before-FROGS group (p < 0.001, Table 2).
Bowel resection was avoided in all 14 patients in the after-FROGS group, whereas 8 patients underwent bowel resection in the before-FROGS group. The bowel resection rate was signi cantly lower in the after-FROGS group than in the before-FROGS group (p = 0.015, Table 4). There were no signi cant differences in postoperative complication and mortality rates within 30 days after hernia presentation between the two groups.

Discussion
We statistically evaluated the effectiveness of FROGS as a new treatment strategy for obturator hernia. The successful rate of manual reduction of FROGS was 100% so far. The result showed that patients can avoid emergency surgery and bowel reduction without increasing postprocedural complications and mortality within 30 days after hernia presentation thanks to FROGS.
Obturator hernia is a rare type of abdominal hernia. Its pathogenesis is attributed to the loss of preperitoneal fat and lymphatic tissues, which normally overlie the obturator canal, thus creating a space around obturator vessels and nerves [12]. Concomitant illnesses, such as chronic obstructive pulmonary disease, constipation, and kyphoscoliosis, could result in increased intraperitoneal pressure and facilitate the growth of the hernial sac [13]. Lean and elderly women are usually affected as they have less preperitoneal fat and several comorbidities that favor the pathogenesis of this condition.
Laparotomy use to be the standard approach for the treatment of obturator hernia since preoperative diagnosis is di cult owing to its rarity and non-speci c signs and symptoms. Ziegler et al. mentioned that "An obturator hernia needs a laparotomy, not a diagnosis" [14]. Likewise, many surgeons believe that emergency laparotomy is the most optimal treatment for possible incarcerated obturator hernias. However, recent advances in imaging techniques, such as computed tomography and ultrasonography, have improved the rate of correct preoperative diagnosis, and this has made less invasive approaches feasible to undertake [2][3][4]. A few studies have described less invasive therapeutic strategies, such as elective surgeries following successful manual reduction [5][6][7]. It was shown that elective surgeries are associated with a higher rate of TAPP implementation. The reason for undertaking laparoscopic approaches less frequently in emergency surgeries could be attributed to the smaller peritoneal cavity resulting from a dilated intestine.
This study aimed to evaluate the e cacy of FROGS as the rst choice of treatment for incarcerated obturator hernias. Usually, patients with obturator hernia have comorbidities, and this makes them unsuitable for emergency surgeries. They should be treated with less invasive therapy in an elective setting, if possible. In addition, it is often the case that some patients and their families do not consent to surgery. Ceresoli et al., showed that emergency surgery for complicated inguinal hernias is burdened by high morbidity and mortality rates in elderly patients [15]. For patients with asymptomatic or minimally symptomatic inguinal hernias, watchful waiting is recognized as an acceptable option [16,17]. Although these studies have mainly focused on inguinal hernias, the results could apply to obturator hernias as well.
The limitation of this study is the relatively small sample size. Further observations and analyses are necessary to con rm the effectiveness of FROGS. Notwithstanding these limitations, manual reduction with FROGS was found to be safe and reproducible and can be the rst treatment choice for patients with obturator hernias. FROGS can be used instead of emergency surgery as a less invasive method to treat patients with obturator hernias while preserving the bowel.

Conclusion
Based on retrospective data of 37 patients, which include 14 patients who underwent FROGS (after-FROGS group) and 23 patients who did not (before-FROGS group), FROGS was found to be safe and reproducible and can be the rst treatment choice for obturator hernia, instead of emergency surgery. More observations and analyses are necessary to further discuss the scope of the indication of FROGS since the sample size is relatively small. However, we believe this result is quite promising.

Ethics approval
This study was approved by the Kurashiki Central Hospital Ethics Committee (the committee's reference number : 3497). All procedures performed in this study that involved human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Consent for publication
Written informed consent was obtained for the academic use of patients' photographs.
Availability of data and material Not applicable.
Competing interest YT, KK, YN, and KK declare that they have no con ict of interest.