The duration of drainage after ventral and incisional hernia mesh repairs. A prospective randomized double blind trial.

Hamila Fehmi | Rafik Ghrissi | Jarrar Mohamed salah | Belhadjkhalifa Mohamed habib | Elghali Mohamed amine | Letaief Rached |

La tunisie chirurgicale - 2020 ; Vol 2020


The duration of close-suction drainage after ventral primary and incisional hernia repairs varies and depends on the surgical teams’ habits. It´s ranging from 3 to 8 days. The aim of this study is to verify if the drainage time of 4 days is suffisient and dont increases the post operative morbidity.

Patients and Methods: A randomized, controlled, double-blinded study is performed. It is comparing an average drainage duration of 6 days (group B), to a duration 30% shorter (4 days) (group A). All patients were treated with extra peritoneal meshes. 

Results: 30 patients in Group A and 28 patients in group B were randomized. They underwent incisional hernia (19 vs. 23), ventral hernia (4 vs. 2) or umbilical hernia (7 vs. 3). A suction drain was used in all cases. The average flow of drainage was respectively in group "A" and "B" on Day 1: 167/173ml; Day 2: 61/64ml; Day 3: 42/50ml; Day 4: 38/47ml, then Group B: Day 5: 52ml; Day 6: 30ml; Day 7: 27ml; Day 8: 20ml. Complications were respectively in group "A" and "B": seroma collection 1 vs 4 cases (p = 0.87); hematoma 1 vs 1 case (p = 0.88); parietal infection in 1 vs 2 cases (p = 0.92). The hospital stay was 6.6 days vs 4.

Conclusion: There was no significant difference in the incidence of seroma, hematoma and wound infection, after prosthetic ventral and incisional hernias repair, between patients who underwent a drainage time for 4 days or more.

Mots Clés

ventral hernia, incisional hernia, surgical mesh, drainage, suction

Introduction :

Recurrences after simple pariétal herniorrhaphy of incisional and ventral hernia can reach 54%, therefore most authors highly recommend prothetic reinforcement [1,2].

Currently, open retro-muscular prosthetic repairs, using polypropylene or polyester mesh is one of the most tolerated and used treatment [3,4]. This surgical procedure lead to significant and rapid local inflammatory response related to the implantation of the prosthesis and to the wide surgical dissection of its integration plan. This local inflammatory reaction produces a serous effusion, justifying for many authors, contact drainages to prevent the creation of seroma or hematoma that could become infected. So far, it is not known whether or not these drains have help the wounds to heal [5]. However, the duration of the drainage is definitely unknown. It still depends on the habits of the surgical teams. In our practice, and although for many authors, the drainage time is an average of 6 days, it sometimes reaches 8 days when it remains productive. This term is often equivalent to the duration of the hospital stay. Patients often refuse to leave the hospital, before that term, with their drains. So the drains are removed if the flow is low (less than 20 ml per day).

Prospective studies have measured the evolution of the acute inflammatory factors in fluid collected in peri-prosthetic space after incisional hernia repair. They showed a rapid decrease in levels of cytokines (IL-1ra, IL-6, IL-10, IL-1 alpha) between the first and the fourth postoperative day [6]. This suggests that a drainage period of 4 days would be sufficient. So the drainage can be removed even if it is still productive.

The first objective of this study is to verify whether the reduction of peri-prosthetic drainage duration to 4 days increases the operative morbidity. The second objective is to check if the number of peri-prosthetic drains influences the operative morbidity.


Patients and methods

Between June 2015 and December 2015, 58 patients aged 30 to 80 years were included in a prospective, randomized double-blind study. The patients had a ventral or incisional hernia extraperitoneal prosthetic repair. We compared the duration of drainage in two groups of patients. In the group "A", the duration of drainage was 4 days, patients underwent a systematic removal of drainage on the 4th postoperative day whatever the drainage rate. In group "B", the duration of drainage was 6 days or more, patients underwent removal of drainage once the fluid drainage was less than 20 ml / 24 hours. 

The post-operative follow-up of the patients and the drainage ablation was entrusted to a surgeon who did not participate in the study. The study protocol was approved by the ethics committee. The participants had expressed an oral consent. So we included in the study all patients who had a ventral or incisional hernia whose neck was greater than 4 cm. The size of defect was measured by a rule after skin marking.

The immune-compromised patients, those affected by kidney failure, cirrhosis, and those under anticoagulant were excluded from the study. All patients received prophylactic antibiotics during anesthesia (2 g of Cefalotin) and a prophylactic anticoagulation postoperatively (Enoxaparin 4000).

Groups A and B were matched by gender, age, Body Mass Index (BMI) and American Society of Anesthesiologists (ASA) score. They differ only by the duration of post-operative drainage. The randomization code was reconciled from the different investigators, nurses and patients.

This code indicates whether the patient was in group A or B. The groups were disclosed on the fourth postoperative day. In this way, patients and investigators were blind.

The study was conducted with the intention to treat.

Patients in group A have had an ultrasound 24 hours after removal of drains to detect parietal collection. However, collection could be removed by ultrasound-guided puncture. the volume of removed fluid collection have to be recorded. after surgery. Fifteen days later, when patients visited outpatients clinic after surgery, ultrasouds were undergone if wound collection were suspected. All patients were discharged immediately after removal of the drainage. All patients were revised by physical examination at the 2nd and 4th weeks of intervention.


All patients underwent general anesthesia and standard regional analgesia by epidural technique. The patients were operated by three senior surgeons. They replicated the same procedure for all patients. The hernia sac was removed partially or entirely. We performed extraperitoneal underlay technique; a polypropylene mesh (20x25 cm) is placed in retro-rectus. The sheath of the large muscles of the abdomen was not opened. The fixation of the prosthesis to the posterior plane was performed by absorbable separate stitches. In all cases one or more close-suction drains were inserted above the prosthesis (less than 4 drains).                   

The choice of the number of drains was left to surgeons. Finally, the anterior fascia was sutured over the prosthesis. We did not need any subcutaneous drainage.

Drainage fluid collection:

The collection of the drainage fluid was daily recorded (Fig 1). To avoid contamination due to handling, close-suction drainage vials were only replaced if they were full. In patients undergoing multiple drains, the total amount was the sum of fluids brought by all drains.

Literature review and statistical analysis:

These were revised databases: the Cochrane Library, EMBASE, PubMed (2005 to 2016) and Scopus. Keywords were "ventral hernia", "incisional hernia", "surgical mesh" and « drainage or suction ». The number of patients needed to conduct the study was determined on "Epi Info" on the basis of the initial hypothesis which was to reduce by 30% (i.e. 2 days: from 6 to 4 days) the duration of active drainage in contact with the prosthesis. The statistical analysis was based on the SPSS 20.0 software. The "Student t test" was used to compare the mean difference. The difference was considered statistically significant when p-value is less than 0.05.


Fifty-eight patients were randomized into two groups, 30 patients in group A who had drainage for 4 days and 28 patients in group B who had a longer period of classical drainage.

Age, gender, grade anesthetic (ASA), type of hernia, operative duration and Body Mass Index were not significantly different between the two groups A and B (Table 1). Patients in Groups A and B (30 vs. 28 patients) were operated for: ventral incisional hernia (19 vs. 23 patients), white line hernia (4 vs. 2 patients) or for umbilical hernia (7 vs. 3 patients) (p = 0.79).

The average size of the hernia neck was 6.13 cm in Group A and 6.25 cm in Group B (p = 0.97). The median surface of the prosthesis was 504 cm² in Group A and 510 cm² in Group B.

The number of drains left in contact with the prosthesis in the two groups A and B was a single drain (24 vs. 16) or multiple drains (2 to 4) (6 vs. 12). The hospital stay was 4 days in group A and 6.61 days in group B.

Postoperative wound Complications:

No postoperative complications were noted (seroma, hematoma, infection, dehiscence) in 29/30 patients in group A and in 23/28 patients in group B (p = 0.49). Seroma collection was found in 1 patient in Group "A", and in 4 patients in Group "B" (p = 0.87).  The seroma were weak to be drained, so they have been respected. In outpatients clinic, fefteen days after surgery, clinical exam was normal for all patients and no ultrasouds were undergone.                 

A hematoma was detected in 1 patient in Group A and in 1 patient in Group B (p = 0.88). Surgical reoperation was required for only the patient in group B who had a large hematoma which was evacuated without removing the prosthesis. A superficial wound infection was noted in 1 patient in Group A and in 2 patients in Group B (p = 0.92). Local cares were sufficient without needing to remove the prosthesis.

Fluids drainage:

The average flow of drainage was respectively in group "A" and "B" on Day 1: 167/173ml;        Day 2: 61/64ml; Day 3: 42/50ml; Day 4: 38/47ml, then Group B: Day 5: 52ml; Day 6: 30ml; Day 7: 27ml; Day 8: 20ml. Until the fourth postoperative day, the amount of fluid collected by the drainage was similar in both groups A and B (Fig 1).


The ventral or incisional hernia repair induces an acute inflammatory response with a release of pro- and anti-inflammatory cytokines during the different phases of the healing process [6-13]. A drain in contact with the prosthesis is probably necessary to prevent the parietal collections.

The drainage:

Actually, the terms of drainage currently meet the habits of surgeons. Generally, drainages are removed once their rate is low, which makes the highly variable drainage duration times up to one week. The drainage flow decreases spontaneously and significantly on the 4th postoperative day [6]. In our study, the average flow of drainage on the 4th postoperative day was almost similar in both groups of patients. Also this rate was not different between patients with single drain and those with multiple drains, this makes useless the multiplication of drains. The morbidity rate was similar in the two groups.

The fluid flow also depends on the surface of the prosthesis in place. In fact, Di Vita et al believe that the parietal repair, using prostheses having a surface greater than 400 cm2, is associated with a high fluid flow and greater release of inflammatory mediators [14]. In our study, all patients were treated with mesh having a surface greater than 500 cm². A wide dissection of the insertion of the prosthesis plane could explain the coming of serous fluid drains on the 4th postoperative day in groupe B. However, the systematic removal of drains in group "A" on the 4th postoperative day (with an average flow rate of fluid comparable to that of group "B") don´t increase morbidity.

Surgery follow up:

It is clear that the duration of patient´s hospital stay, in patient who undergone prothetic reinforcement, is related to postoperative pain, duration of drainage and complications. Many authors, especially in extra abdominal surgery, have shown that drainage increases hospital stay duration [15], but can also be source of postoperative pain [16]. Others, go even further, and think that drainage is a foreign body in contact with the prosthesis, so there is a risk that the prosthesis may become infected [17].

The seroma were more frequent in group "B" (14%) compared to group "A" (3%) but without significant difference. Wound Hematomas were also rare (one case each).


We underwent parietal polypropylène prosthetic reinforcement for ventral and incisional hernia whose neck was greater than 4 cm. There was no significant difference in the postoperative morbidity between patients who underwent a drainage time for 4 days or more.


Table 1: Patients characteristics


Group A


Group B (n=28)



Age (median)


55.77 years





Gender:     Males








Defect size (cm)




BMI: median




Hernia type

                Incisional Hernia

                Umbilical Hernia

                White line Hernia













 Prosthesis surface (median in  cm²)




Number of Drains:   1

                                  2, 3 or 4            







Hospital stay duration (days)





*NS : Non significant


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