Open surgery
Open repair remains the most common approach to large CDH defects not amenable to a tension-free, primary repair. Type of incision, defect closure (patch or muscle flap), shape of patch and technical adjuncts (antireflux surgery, abdominal wall closure) must be considered.
Repair of large CDHs requires optimal exposure of the defect achieved by a thoracic or abdominal (ie, subcostal and midline) incision. Thoracotomy was historically the most frequent approach, nowadays only 1%–5% of pediatric surgeons repair left-sided CDH via a thoracotomy.34 35 Although a thoracic approach may facilitate placement of pericostal sutures, hence strengthening the patch repair, it is associated with an increased risk for musculoskeletal deformities and higher rate of surgical reinterventions within the first year of life, especially for severe acute gastrointestinal complications.34 36
The abdominal approach with a subcostal incision is preferred by most pediatric surgeons. A transverse upper quadrant incision is argued to provide the best exposure in neonates and to better withstand increases in intra-abdominal pressure, hence reducing the risk for an incisional hernia.37–39 Conversely, Waag et al. have advocated for a vertical midline incision due to improved exposure of the defect,40 option of increasing the incision beyond the umbilicus and improved cosmesis, with a possibly reduced risk of incisional hernia.41
Patch repair
Patch repair is often used as a surrogate marker for large defects,35 but it is unclear what type of patch material should be used: permanent (polytetrafluorethylene, PTFE), biosynthetic (eg, small intestinal submucosa, dermal collagen), or composite patches.42 ,36 43 44 The types of patch material reported in the literature are summarized in figure 2. Current evidence, mainly based on cohort studies, recommends a non-absorbable PTFE/Gore-Tex patch (WL Gore and Associates, Newark, Delaware) because of its durability compared with biologically absorbable material.5 7 45–47 However, studies show varying results.13 48–53 A recent meta-analysis reported similar mortality rates, risk of adhesive bowel obstruction and incidence of gastroesophageal reflux disease (GERD) after synthetic and biological patch repair.49 Among biologically absorbable materials, intestinal submucosal Surgisis (Cook Medical, Bloomington, Indiana) was one of the earliest patches, hence is the most studied in the literature to date.48 50–55 Surgisis allows for full incorporation of the patch into the native tissue; however, resorption starts within 2 weeks which may explain the high recurrence rate due to insufficient scarring to withstand the abdominal pressure.49 A recent industry refinement on Surgisis is Biodesign (Cook Medical), which displays faster rehydration and more blood vessel ingrowth. Permacol (Medtronic, Minneapolis, Minnesota) uses a cross-linked acellular porcine dermal collagen to improve long-term tensile strength.49 56 Mitchell et al. showed no recurrence in eight cases after Permacol repair (median follow-up: 20 months) compared with a 29% recurrence rate after Gore-Tex patch repair (median follow-up: 57 months).56 Unfortunately, sufficient data on the outcomes of newer materials are lacking, but the prospective multicenter cohort ‘Defect Study’ might provide answers in the future.57
Figure 2Technical considerations in congenital diaphragmatic hernia (CDH) repair. PTFE, polytetrafluorethylene.
The goal of a tension-free, oversized closure of the diaphragm is especially important in large defects. Synthetic patches do not grow with the patient, which can result in recurrence in the long term. An oversized ‘cone’-shaped patch provides additional abdominal domain which may offset the development of tension between the patch and defect edges, and in one study resulted in an equivalent recurrence rate to that of primary repairs.58 ‘Cone’-shaped patches try to replicate the shape of the diaphragm to facilitate a more physiological thoracic volume, with improved respiratory physiology, and a lower recurrence rate.46 47
Muscle flap repair
Muscle flap repair is suggested as an alternative approach in very large defects or recurrent CDH.55 59–68 Even though reverse latissimus dorsi (RLD) and abdominal wall muscle flap repairs have been described since 1983 and 1962, respectively, studies on the application and outcome of muscle flap repairs are limited.68 69
An abdominal wall muscle flap is facilitated by a transverse or subcostal abdominal incision that is 2–3 cm below the costal margin which enables superior flap-based separation of the external and internal oblique muscle layers and closure of the diaphragmatic defect with the transversus abdominis-internal oblique muscle flap turned inward.67 It is mainly used in initial repair of large defects in neonates.55 59–67 The advantages are the potential for growth and the lack of a foreign body reaction. However, the required muscular dissection could result in an abdominal wall bulge.65 67 Large CDH defects are inherently associated with a higher risk of musculoskeletal deformities irrespective whether an abdominal wall muscle flap or patch is used.70 The recurrence rate of this technique ranges from 0% to 20%.55 59 62 66 71 Nasr et al. found no significant difference in chest wall deformities, bowel obstruction or mortality between patch (n=32) or abdominal wall muscle flap (n=19) repairs.55 The largest study comparing abdominal wall muscle flap and patch repair showed no statistically significant difference in recurrence (abdominal wall muscle flap: 3.5%, n=2/57 vs patch: 8.8%, n=3/34).62 Abdominal wall muscle flap repair is feasible on extracorporeal membrane oxygenation (ECMO), and there was no difference in on-ECMO bleeding complications compared with patch repair in small cohorts.59 63 65 Only one study described the abdominal wall muscle flap in recurrent CDH repair; however, the benefit of this technique compared with others is unclear.64
An RLD muscle flap repair has several benefits: (1) sustained blood supply by lumbar-perforating vessels minimizing flap atrophy, (2) potential for ‘neodiaphragmatic’ function enabled by a phrenic to thoracodorsal neural anastomosis and (3) ability to grow with the child.60 68 The anticipated hemodynamic instability associated with large defects and the longer operative time associated with an RLD muscle flap repair argues against its use for the initial repair.72 After cardiopulmonary stabilization, subsequent growth and development of a patient, the RLD muscle flap with neuroanastomosis can be performed at a later stage.60 72 In the event of GERD, antireflux surgery could be addressed in the same procedure.60 61 72 An RLD muscle flap could be considered as an alternative in recurrent CDH or as a staged approach following patch repair resulting in recurrence, chest wall deformity or other thoracic complications.60 68 72
As an alternative to muscle flaps, Toldt’s fascia flap repair has been described in seven patients with large defect, but long-term data or benefits of this technique—published in 2005—are absent.73
Procedural adjuncts for large defects
Surgical management of large diaphragmatic defects may require consideration of procedural adjuncts compared with small defects (figure 1), including antireflux surgery and staged abdominal wall closure. Large defects have a higher risk of developing GERD requiring antireflux surgery later in life.74 The incidence reported in the literature varies74–76: a study of 126 patients with CDH reported that 55.6% developed GERD and 33.3% received a fundoplication.74 The apparent association of GERD requiring fundoplication with large defect CDH has prompted consideration of ‘preventative’ antireflux surgery at the time of CDH repair. A prospective, multi-institutional study showed no benefit to a preventative fundoplication during the initial patch repair in high-risk patients: it did not prevent—in fact, it increased—the likelihood of failure to thrive, the need for tube feeding, the occurrence of oral aversion and the necessity for curative redo fundoplication later in life.76 Current evidence does not support a ‘preventative’ fundoplication at primary repair, and antireflux surgery or other antireflux interventions should only be considered in the context of failed medical management.5 75 76
A potential difficulty at the end of the initial repair of large and occasionally small defects lies in the severity of viscero-abdominal disproportion which can present challenges to abdominal wall closure. A ‘cone’-shaped diaphragmatic patch can partially compensate for a small abdominal cavity, creating an estimated 20 mL more volume.36 However, in severe cases, a staged abdominal wall closure (e.g., temporary silo, patch) mitigates the risk of abdominal compartment syndrome and reduces the risk of early recurrence.77 In MIS repair, tackling viscero-abdominal disproportion is more challenging and carries a higher risk of gastrointestinal complications. Hiradfar et al. describe a two-staged endoscopic repair of a large defect in a 4-month-old boy: a laparoscopic transverse fasciotomy was performed inducing an iatrogenic ventral hernia, and a pneumoperitoneum was maintained over 2 days until a thoracoscopic patch repair was possible.78
Minimally invasive surgery
Minimally invasive repair has been shown to be safe and feasible for CDH, particularly for stable infants with small defects. With increased experience, many of the initial contraindications have been challenged or even refuted (e.g., stomach-up/liver-up,6 21 ‘C defects,6 79 need for patch,15 right-sided CDH,23 need for perioperative high-frequency oscillatory ventilation,80 ECMO,9 81–84 and associated anomalies85). Current recommendations mainly rely on cohort studies of varying size and quality, and data on long-term outcomes are sparse.
Threshold for a patch repair should be similar in MIS and open repair with a goal of achieving a tension-free closure.7 29 31 32 86 Although higher recurrence risks have been associated with MIS (almost exclusively thoracoscopic) repair, increased experience has led to an observed decrease in recurrence rates.24 86 Recent studies have shown a similar recurrence rate in thoracoscopic and open repair of selected patients.6 8 81 87 In September 2023, Shah et al. published the first direct comparison of thoracoscopic and open repair of ‘larger’ CDH defects, defined as a ‘B’ defect with patch repair or a ‘C’ defect.6 Even though the study tried to account for bias in disease severity, patients with open repair had a significantly lower observed/expected lung-to-head ratio, observed/expected total lung volume, more ‘C’ defects, liver-up and a greater ECMO necessity. Nonetheless, there was no difference in operative time, intraoperative acidosis and recurrence rate between MIS and open surgery.6 Despite these findings, the authors proposed open repair in patients with ‘D’ defects, liver-up, ECMO necessity and high preoperative ventilation parameters.6 Among pediatric surgeons, there is a call for prospective, multicenter registries and development of trials to identify which patients with CDH most clearly benefit from a thoracoscopic repair.22 36
Reduced risk of bowel obstruction would favor an MIS approach; but bowel obstruction has been studied less than recurrence. Studies in small cohorts show a decreased bowel obstruction rate after thoracoscopic repair.9 52 88–91 The CDHSG showed a five times lower risk of adhesive small bowel obstruction requiring an operation prior to discharge in thoracoscopic compared with open repair, but the number of ‘C’ and ‘D’ defects repaired by MIS was low.9 Zahn et al. showed that small bowel obstruction after thoracoscopic repair was only associated with CDH recurrence and not adhesions, even in cases of thoracoscopic Gore-Tex patch repair.90 This might be related to the reduced peritoneal irritation eliciting an inflammatory response (and therefore adhesions) in thoracoscopic repair.
Technical considerations in MIS repair of large defects
Evolution of MIS and improved surgical techniques resulted in decreased operative time and recurrence rates, but also expanded the selection criteria to more complex CDH cases. Safe reduction of herniated abdominal organs, suturing and tensionless defect repair are the main challenges of MIS in CDH repair. Several innovations have been suggested to facilitate the procedure.
To overcome the challenge of reduction, particularly in larger defects, studies have suggested insertion of more than three ports,33 86 92–94 placement of mesh,6 a temporary increase in CO2 insufflation rate,86 92 94 or transthoracic traction stitches in the middle of the defect to keep the organs reduced when suturing.93
Intracorporeal suturing remains one of the most difficult and time-consuming steps in the repair of moderate to large defects resulting in prolonged operative time and conversion to open repair. Several techniques have been described to facilitate thoracoscopic knot tying and can be categorized into intracorporeal84 95 or extracorporeal.29 47 86 92–94 96 97 He et al. described an extracorporeal technique combining a granny and surgeon’s knot. They report no conversion to open repair or recurrence in 26 cases at a median follow-up of 13.7 months.97 A similar extracorporeal-assisted intracorporeal method has been suggested with a sliding knot.98 Further techniques include non-absorbable helicoidal tacks95 and unidirectional barbed knotless sutures.84
Different techniques and devices have been described to aid pericostal suturing in MIS, particularly when no posterolateral diaphragmatic rim exists. The most common described technique is to pass a needle directly through a small incision in the skin, the intercostal space, the diaphragm or patch and then back through the same incision. The knot tying takes place extracorporeally and multiple knots can be buried in the subcutaneous tissue.25 26 32 81 99 An alternative method is similar to the percutaneous internal ring suturing technique for inguinal hernia repair: different techniques and devices have been described to aid in the fixation of the diaphragm or patch to the ribs with mattress sutures.79 92–94 100 Mansour et al. suggest anchoring the patch around the ribs using Endo Close.86 Lapa-her-closure (Hakko, Chikuma, Japan) is a 19-gauge needle with a built-in wire loop to hold and release sutures intracorporeally and to facilitate securing the patch around the ribs.29 Michel et al. report a ‘T-shaped’ placement of sutures to achieve primary thoracoscopic repair in ‘large B-defects’ with close to 50% absence of the diaphragm; no recurrence occurred in any of the seven cases over a median of 3.5 years of follow-up.12
Different thoracoscopic patch onlay techniques have been proposed to reduce the higher recurrence rate observed in MIS. Most studies describe a ‘cone’-shaped, single layer of Gore-Tex patch.29 31 32 81 Alternatively, Kamran et al. proposed a double-layered repair of Marlex (Becton Dickinson, Franklin Lakes, New Jersey) (thoracic side) and Gore-Tex (abdominal side) mesh in ‘larger’ B defects, or leaving a hernia sac as a natural underlay to the prosthetic buttresses.33 Shah et al. describe a sandwiched approach of Vicryl mesh (abdominal side) to facilitate reduction and induce scarring, and Gore-Tex on top.6 A biological mesh (Surgisis) underlay has been proposed to reduce the recurrence rate in both thoracoscopic primary and patch repair.25 26 Thoracoscopic repair with a single layer of biological mesh, Surgisis, resulted in early and frequent recurrences, hence is not advised.32 Recently, a novel, self-expandable patch has been tested in an inanimate CDH model to successfully repair ‘C’ and ‘D’ defects.101 A single case report describes using the Gerota fascia to repair a large defect thoracoscopically.102 Technical innovation has driven the evolution of MIS in CDH improving operative times, outcomes especially in small defects, and reducing rates of conversion to open repair in larger defects. However, the variability in reported techniques and the very limited number of cases with follow-up makes it difficult to determine which approaches offer the greatest outcome benefit.22 33
Anesthetic considerations
The thoracoscopic approach to large defects increases intraoperative challenges for anesthetists due to potentially severe hypercapnia and acidosis caused by CO2 insufflation which compresses and reduces ventilation of the already hypoplastic lung, and results in systemic CO2 absorption. Intrathoracic pressures may be elevated by ventilatory pressure requirements compounded by CO2 insufflation causing decreased venous return. In addition, patients with CDH with large defects have an increased oxygen demand due to their hypoplastic lungs.103 Hypoxia, CO2 accumulation and acidosis could further aggravate pulmonary hypertension, resulting in a vicious cycle.104
Intraoperative hypercapnia and acidosis have been described in multiple retrospective studies105–109 and one pilot randomized controlled trial.110 Other studies in small cohorts demonstrated no difference in hypercapnia and acidosis between MIS and open repair, even after ECMO.6 81 111 A ‘low pressure, slow insufflation technique’ to establish capnothorax is suggested to allow the neonate to gradually adapt to the CO2 insufflation and potentially avoid spikes in hypercapnia.32 105 108
The adverse effect of perioperative acidosis and hypercapnia on the long-term outcome remains controversial. Bishay et al. reported that intraoperative acidosis was associated with a decrease in cerebral hemoglobin oxygen saturation in six patients during thoracoscopic CDH or esophageal atresia/tracheoesophageal fistula repair that could potentially contribute to ischemic brain injury.109 Okazaki et al. describe normal neurodevelopment after thoracoscopic repair, even though significant intraoperative hypercapnia and acidosis occurred.112 Costerus et al. showed that intraoperative regional cerebral oxygen saturation remained within clinically acceptable limits during periods of acidosis, and neurodevelopmental outcomes (in those available for evaluation) at 24 months were within normal range.113 Long-term outcomes beyond infancy are lacking; however, the attribution of morbidity to the surgical technique rather than to the known consequences of CDH pathophysiology will always be a challenge.
ECMO before thoracoscopic repair is feasible, but experience is limited.6 81–84 86 Many surgeons consider intraoperative or preoperative ECMO a contraindication for thoracoscopic repair.114 Nevertheless, Schlager et al. reported no increase in operative morbidity or mortality for six patients with successful thoracoscopic repair after ECMO with similar recurrence rates compared with open repair.82 However, most post-ECMO patients with attempted MIS repair (n=15/21) in the study were converted. Budzanowski et al. published a cohort of six post-ECMO patients with a thoracoscopic patch repair81: there was no significant difference in the perioperative blood gas parameters between thoracoscopic and open repair, but two of six patients were converted to open repair due to diaphragmatic agenesis.81 Prenatal intervention with fetoscopic endoluminal tracheal occlusion has improved pulmonary hypoplasia in severe CDH cases contributing to reduced severity of pulmonary hypertension.115 It can be speculated that improved pulmonary outcomes in these patients might encourage a greater shift from open surgery to MIS.
Laparoscopy
Most studies on MIS in neonatal CDH only include the thoracoscopic approach.6 7 12 16 20 21 23 25 26 28–30 32 33 79–88 91–99 102 104–108 110 112 113 The CDHSG showed that 17.2% of MIS in all CDH cases were performed using laparoscopy.35 Possible benefits of laparoscopy are reduced risk of visceral injury, inspection for abdominal anomalies and easier conversion to an open approach. A case of laparoscopic patch repair in a neonate with a large Bochdalek hernia has been reported.116 The main indication for a laparoscopic approach is a Morgagni hernia which will be addressed in the following section.
