Evaluation of Four-Hand Reduction for Obturator Hernia with the Guidance of Sonography (FROGS) As a New Treatment Strategy for Obturator Hernia: A Single-Center Study

Obturator hernia is an uncommon but important cause of intestinal obstruction. Delayed treatment can be fatal. Emergency surgery is considered the most effective treatment; however, patients with obturator hernia usually have comorbidities, which precludes them from emergency surgery. This study aimed to evaluate the effectiveness of Four-hand Reduction for Obturator hernia with the Guidance of Sonography (FROGS) as a new treatment strategy for obturator hernia. No signicant differences were observed in age, lesion side, duration of symptoms, the diameter of the prolapsed bowel, and predisposing factors. The body mass index was signicantly lower in the after-FROGS group than in the before-FROGS group. Manual reduction was successfully performed 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.


Abstract Background
Obturator hernia is an uncommon but important cause of intestinal obstruction. Delayed treatment can be fatal. Emergency surgery is considered the most effective treatment; however, patients with obturator hernia usually have comorbidities, which precludes them from emergency surgery. This study aimed to evaluate the effectiveness of Four-hand Reduction for Obturator hernia with the Guidance of Sonography (FROGS) as a new treatment strategy for obturator hernia.

Methods
Since November 2019, we have tried FROGS in all patients with obturator hernia at the emergency room. All the patients were female. We retrospectively compared the clinical data of 14 patients who underwent FROGS (after-FROGS group) with those of 23 patients who did not (before-FROGS group).

Results
No signi cant differences were observed in age, lesion side, duration of symptoms, the diameter of the prolapsed bowel, and predisposing factors. The body mass index was signi cantly lower in the after-FROGS group than in the before-FROGS group. Manual reduction was successfully performed 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 signi cant differences in postoperative complications and mortality within 30 days after hernia presentation between the two groups.

Conclusion
Manual reduction with FROGS was found to be safe and reproducible and can be the rst treatment choice for obturator hernia.

Background
Obturator hernia is a rare type of abdominal hernia that accounts for < 1% of all abdominal hernias [1]. Although arriving at a de nite preoperative diagnosis was di cult in previous years, it has become easy following the use of advanced imaging techniques [2][3][4]5]. Obturator hernia usually develops in elderly, thin, and multiparous women who often have comorbidities and other debilitating conditions, which can preclude them from emergency surgery; therefore, the postoperative mortality rate after emergency surgery is high [6,7]. However, once diagnosed, emergency surgery is usually performed because delayed treatment can lead to intestinal ischemia and subsequently, perforation [1]. Few reports have described a successful manual reduction of obturator hernia [8][9][10]. There is no controversy about whether manual reduction (with or without elective surgery) or emergency surgery is more effective, since many general surgeons believe that emergency surgery is the only effective treatment for this condition. Four-Hand Reduction for Obturator Hernia with the Guidance of Sonography (FROGS) is a simple technique that we devised to treat obturator hernia in the emergency room. This study was performed to evaluate the effectiveness of FROGS as a new treatment strategy for obturator hernia.

Study design
The clinical data of all patients with obturator hernia who were admitted to the Department of Surgery at Kurashiki Central Hospital between April 2016 and September 2020 were retrospectively reviewed. We implemented FROGS in the emergency room as the rst choice of treatment since November 2019. We compared the clinical data (age, sex, body mass index, site of the hernia, predisposing factors, type of surgery, hernia size, complications, hospital stay, outcome, and follow-up) of patients who underwent FROGS (after-FROGS group) with those of patients who did not (before-FROGS group).
Steps of FROGS FROGS is a bed-side reduction method in the emergency room for obturator hernia under real-time sonography guidance. This technique requires two surgeons, which is why it is a "four-hand" technique. Before initiating this procedure, the presence of obturator hernia (a hernia sac between the adductor longus and the pubis) has to be con rmed. While the surgeon con rms its presence, the assistant supports the patient to keep the hip joint exed and rotated externally so that the hernia sac can be visualized (Fig. 1).
Step 1: The surgeon places the transducer in the left hand on the patient's groin area (just cranial to the inguinal ligament) while the right hand pushes the hernia sac. Meanwhile, the assistant places the hip and knee joints in the exed position.
Step 2: The assistant slightly rotates the hip joint laterally, thereby widely opening the hernia ori ce (Fig. 2).
Step 3: The assistant places the hip joint and the knee joint in an extended position (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 has to keep pushing the hernial sac. In Step 3, the surgeon pushes it even harder. The muscles along the obturator canal relax so that the hernia sac can be reduced. Two people continue this maneuver repeatedly until the hernia sac is completely pushed back. This movement may be reminiscent of a frog moving his 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. The continuous variables are expressed as the mean ± standard deviation, and the categorical variables are expressed as absolute numbers and percentages. All variables were analyzed using Student's t-test for continuous variables and the χ 2 test or Fisher's exact test for categorical variables. A p value < 0.05 was considered statistically signi cant.

Results
A total of 37 patients with obturator hernia were admitted to the Department of Surgery at Kurashiki Central Hospital between April 2016 and September 2020.
Until FROGS was implemented, 23 patients were already 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 the patients are summarized in Table 1 at the end of this article. All patients were female. Obturator hernia was diagnosed in all 37 patients preoperatively based on a computed tomography scan. There were no signi cant differences in age, lesion side, duration of symptoms, the 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 that in the before-FROGS group (p = 0.0158, Table 2).  Manual reduction was successfully performed in all 14 patients in the FROGS group (success rate of 100%). In the before-FROGS group, 14 patients underwent manual reduction, 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, the successful manual reduction was performed in only one patient who underwent elective surgery, which was performed using TAPP. Emergency surgery could not be performed on one patient because of severe heart failure; this patient died 6 days after admission. The other 21 patients underwent emergency surgery: 17 underwent laparotomy and 4 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 could be 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). No signi cant differences were observed in postoperative complication and mortality rates within 30 days after hernia presentation between the two groups.

Discussion
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 [11]. Concomitant illnesses, such as chronic obstructive pulmonary disease, constipation, and kyphoscoliosis could result in increased intraperitoneal pressure and facilitate the growth of the hernia sac [12]. Lean and elderly women are usually affected as they have less preperitoneal fat and several comorbidities, which favor the pathogenesis of this condition.
Laparotomy is 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. have mentioned that "Obturator hernia needs a laparotomy, not a diagnosis" [13]. 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, which has made less invasive approaches feasible to undertake [2][3][4]. Few studies have described less invasive therapeutic strategies, such as elective surgeries following successful manual reduction [5][6][7]. Elective surgeries were shown to be 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, which 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 [14]. For patients with asymptomatic or minimally symptomatic inguinal hernias, watchful waiting is recognized as an acceptable option [15,16]. Although these studies have mainly focused on inguinal hernias, the results could apply to obturator hernias as well.
In our study, emergency surgeries could be avoided in asymptomatic or minimally symptomatic patients because of the implementation of FROGS. Some of these patients underwent safe elective TAPP repair, while in others, comorbidities or family wishes were decisive factors. Irrespective of whether elective surgery was performed or not, bowel resection could be avoided in all patients. In addition, the short-term prognosis between the after-FROGS and before-FROGS groups was comparable. Although the balance between the risks of elective surgery versus the risks of a watchful approach is still a matter of debate in the absence of speci c recommendations for elderly patients [14], a watchful approach could be a choice based on this result and the literature.
Although patients who do not undergo elective surgery are still at risk of recurrence, FROGS can be reproducible in cases of recurrence owing to its high success rate. Therefore, we believe that FROGS can be the rst choice of treatment in any case of obturator hernia incarceration. The mechanism of FROGS is unclear and may be complex. However, we believe that complex coordinated movements of muscles around the obturator canal may have an important role. The driving pressure generated by these movements helps surgeons to reduce the hernia sac. In addition, at some point during this maneuver, the obturator canal may be maximally relaxed (usually in Step 3, based on our experience), and by repeating FROGS, we can eventually nd this particular point.

Declarations
Ethics approval and consent to participate: All procedures performed in this study, which 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. Written informed consent was obtained for the academic usage of patients' photographs.
Consent for publication: Written informed consent was obtained for the academic usage of patients' photographs.
Availability of data and material: Not applicable. Figure 1 The surgeon is con rming the hernia sac between the adductor longus and the pubis. The assistant supports the patient to keep the hip joint exed and rotated externally to ensure the hernia sac is well-visualized.  The assistant places the hip joint and the knee joint in an extended position.