Laparoscopic and robotic specimen retrieval system (Modified Nadiad Bag): Validation and cost-effectiveness study model.

AIM: To construct and validate a cost-effective indigenously made retrieval system (Modified Nadiad bag) in minimal access urology.
METHOD: The components of the modified Nadiad bag are a polyethylene roll, fishnet thread, and a 5 Fr ureteral catheter. The bag is indigenously made in our institute and used for organ retrieval after proper sterilization. The video recordings of entrapments and retrievals done over the past few months were reviewed. The procedures under review in which the bag was used were: Robot Assisted Radical Prostatectomy (50 cases), laparoscopic radical nephrectomy (50 cases), laparoscopic simple nephrectomy (50 cases) and laparoscopic adrenalectomy (18 cases). We also compared the retrieval time with experts and novices.
RESULTS: The retrieval times, the organ size (largest dimension) and specimen weight were records for each case. Multivariate analysis of the data was done and we extrapolated the retrieval time with organ size, specimen weight and expertise of the surgeon. There was no significant difference among expert surgeons and novice surgeons with regards to retrieval times (p value = 0.29), with regards to organ size (p value = 0.83) and with regards to specimen weight (p value = 0.99).
CONCLUSION: Our design of retrieval system offers a cost-effective option which is easy to make, without the risk of tumor seeding and without the need for separate access sheath. It's a retrieval system which has proved its efficacy in laparoscopic as well as robotic procedures with no bearing on the expertise of the surgeon involved.

INTRODUCTION

Specific retrieval forms an integral part of any ablative procedure. The key requisites for any successful entrapment of the specimen include expeditious retrieval and ensuring that the specimen is not mutilated which may hamper proper histological interpretation. There are also concerns regarding oncological principles such as spillage.

The currently available specimen retrieval bags cost in the range of 25–100 USD.[1234] All laparoscopic surgeons have their indigenous ways of entrapping, the specimen using the available glove finger, etc.[4] However, the drawbacks of all these indigenous entrapment materials include the inability to keep the ‘mouth’ of the entrapment device open. This increases the difficulty for entrapment besides adding to the operating time. This novel ‘homemade’ bags do not ensure retrieval without spillage.

We have devised a solution, a bag which is not only cost effective but is also as effective as the available devices. This bag was initially described as the Nadiad Bag.[5] We performed a validation study in various urological procedures and assessed the safety, efficacy and cost-effectiveness. We also evaluate the efficacy by validating the entrapment time and retrieval time.

Aim of study

The aim of this study was to construct and validate a cost-effective indigenously made retrieval system in minimal access urology.

MATERIALS AND METHODS

Device specifications

The components of the retrieval bag are a transparent plastic bag roll, fishnet thread and a 5 Fr ureteral catheter. The plastic bag rolls have a tubular construction throughout their length and three different sizes are available in the market [Figure 1a].[6] These bag rolls are unwound to the required length and cut according to the individual requirement [Figure 1b]. One end of the plastic bag roll is stitched completely and sealed which becomes the base of the bag [Figure 1c]. The corners of the other end (mouth) of the bag are cut up to 3 cm [Figure 1d]. The other corner of the mouth being cut in a similar manner [Figure 2a]. The plastic slip so created after cutting the corner is folded outwards on itself to create a tunnel [Figure 2b]. The folded edge is then stitched to create a tunnel [Figure 2c]. In a similar manner, the other slip of plastic is folded outwards on itself and stitched to create a second tunnel [Figure 2d]. The final bag so created has a sealed lower end and the mouth of the bag with two tunnels at the edges [Figure 3a and b]. A loop is created at the end of the fishnet thread. The ureteric catheter is passed through this loop for ease of insertion of catheter in the tunnel [Figure 3c]. The folded tunnel accommodates the 5F ureteral catheter and fishnet thread [Figure 4]. Finally, the bag is folded compactly with rubber bands wound tightly around it and sealed in a plastic bag and sterilised using plasma steriliser before use.

Figure 1

(a) Plastic Bag Rolls (b) Bag roll cut to a required length (c) Lower end of the bag stitched and closed (d) Corner of the open end being cut

Figure 2

(a) Opposite corner of the open end being cut (b) Slip of plastic being folded outward to create a tunnel (c) Folded edge is stitched to create a tunnel (d) Other slip also folded and stitched to create another tunnel

Figure 3

(a) Bag has a stitched bottom end and mouth with two tunnels. (b) Mouth of the bag with two tunnels. (c) 5 Fr ureteric catheters passed through fishnet loop

Figure 4

Tunnelling of the ureteric catheter along with the fishnet thread

During the operative procedure, the bag introduction is performed through the 10-mm port with the help of an atraumatic grasper without any special introducer sheath. Two laparoscopic instruments are required to open, place the specimen within and close the bag [Figure 5a-c]. Once the specimen is secured in the bag, the ureteric catheter is pulled out with a laparoscopic grasper and the fishnet thread is pulled to close the open mouth of the bag. The bag can be retrieved though any of the ports by extending the incision if required. The bag is manufactured at Muljibhai Patel Urological Hospital research laboratory.

Figure 5

(a-c) Intraoperative pictures

Ever since its induction in routine ablative laparoscopic procedures at our institute we have made two modifications as follows: (1) The use of fishnet thread instead of nylon sutures as fishnet thread is more compliant with plastic since it does not tear through the plastic bag when pulled which was the case with nylon thread and fishnet thread is more economical. (2) The lower end of the bag is stitched on a sewing machine which was previously sealed with an autoseal device. Earlier bags sealed with an autoseal device often showed dehiscence and opened when the specimen was placed.

It is available in three sizes. The sizes are as follows [Table 1]:

Table 1

Dimensions of three available sizes of the modified nadiad bag

	Small	Medium	Large
Length (cm)	20	23	26
Breadth (cm)	10	16	20
Width (cm)	7	12	16

The key feature of the bag and the idea which makes this an innovation is the ureteric catheter. In all indigenous bags or the homemade bags, there is a shortcoming that the mouth of the bag cannot be kept open as the plastic keeps on folding on itself. We thought that we need to device a mechanism by which the mouth remains open. This can be kept open using a stiff material. The material can be a ureteric catheter.

Cost implications

Another major shortcoming associated with the commercially available retrieval systems is the cost ranging from $ 25 to 100[1234] [Table 2].

Table 2

Comparison of cost of currently available retrieval systems in the market

Bag	Company	Cost ($)
Endopouch	Ethicon	100[1]
Endocatch gold 10-mm Bag	Covidien	60[2]
Pleatman Sac	Gyrus ACMI	25[3]
Ponsky Endosac	U.S. Endoscopy	60[4]
Homemade glove Bag	Taipei , Taiwan	1.25[4]
Nadiad Bag	Nadiad, India	1.20

The microcosting for our innovation is only over 1 USD [Table 3].

Table 3

Cost split up

Material	Cost (RS.)	Total
Cost of the plastic material	2.50	Total=Rs. 77.50 ($1.20)*
Cost of the ureteric catheter	70
Cost of the thread	2
Cost of the machine stitching	3

*1 US Dollar=64.51 Indian rupees (as on 27 June 2017)

Study design

The present study was conducted at Muljibhai Patel Urological Hospital, Nadiad, India. The video recordings of entrapments and retrievals done over the past few months were reviewed. The procedures under review in which the bag was used were as follows: robot-assisted radical prostatectomy (50 cases), laparoscopic radical nephrectomy (50 cases), laparoscopic simple nephrectomy (50 cases) and laparoscopic adrenalectomy (18 cases). We also compared the retrieval time with experts and novices. The compatibility and permeability testing of the bag was performed using the innovative saline fill technique.

RESULTS

The retrieval times for all the above-mentioned procedures were collected. The organ size (largest dimension) and specimen weight were also recorded for each case [Table 4].

Table 4

Data summary

Procedure	Organ size (cm)	Specimen weight (g)	Retrieval time	Surgeon 1*	Surgeon 2†
Robot-assisted radical prostatectomy	32.5±11.65	37.8±10.97	2:20 min±71.68 s	1	49
Lap adrenalectomy	71.5±23.05	96.5±158.48	2:35 min±54.12 s	17	1
Lap simple nephrectomy	147.9±34.46	329.3±216.17	4:19 min±101.3 s	11	39
Lap radical nephrectomy	162.24±26.35	560.34±260.05	4:55 min±140.38 s	5	45

*Surgeon 1: Laparoscopic surgeon with an experience of >30 cases, †Surgeon 2: Urology resident and laparoscopic surgeon with experience <30 cases

The saline fill test was done in all models of the bag. It did not reveal any leak of saline.

Multivariate analysis of the data was performed, and we extrapolated the retrieval time with organ size, specimen weight and expertise of the surgeon [Table 5]. Statistical tests applied were Levene's test for equality of variances and t-test for equality of means. There was no statistically significant difference between expert surgeons and novice surgeons with regard to retrieval times (P = 0.29), with regard to organ size (P = 0.83) and with regard to specimen weight (P = 0.99).

Table 5

Group statistics

Surgeon	n	Mean	Std. deviation	Std. error mean
Retr_Time
1	37	220.97	139.494	22.933
2	131	247.20	104.334	9.116
Organ_Size
1	37	111.24	50.256	8.262
2	131	109.18	65.266	5.702
Spec_Wt
1	37	286.43	327.022	53.762
2	131	286.69	274.352	23.970

DISCUSSION

Even since the introduction of the laparoscopy as a modality in the realm of urology, it has gained widespread acceptance for various reasons such as shorter hospital stay, less postoperative pain and better cosmesis. However, one of the challenges faced in laparoscopic ablative surgeries is the extraction of the excised organ specimen.

Direct specimen retrieval attempted initially often required larger incisions and thus increasing the risk of an incisional hernia besides compromising cosmesis.

With the intent to tackle this challenge Clayman and associates designed the first organ bag (LapSac), especially for laparoscopic nephrectomy.[7] Since then a number of versions of specimen retrieval systems have been developed and made commercially available for specimen retrieval intact as well as morcellation with specimen retrieval.

Currently, commercially available retrieval systems individually have their own advantages and disadvantages. The Pleatman sac by design has its mouth continuously open allowing the specimen placed inside to slip out while extraction. The Endocatch bag turns irretrievable once the purse string is activated closing and tearing of the plastic bag. The LapSac bag (Cook Urological) which is one of the most commonly used bags for morcellation of nephrectomy specimen often requires placement of two or three additional ports to manoeuvre specimen into the bag. This also further demands a learning curve to use this bag. The Lap Bag, Extraction Bag, Endobag, Endopouch and Endocatch are some retrieval systems which require an additional introducer sheath to deploy the bag. The Espiner bag has been proven to have poor impermeability.[8]

The material used in manufacturing of the bags does play an important role in the success or failure of retrieval of an intact specimen. Singhvi and associates analysed the physical properties of the endoscopic retrieval systems and revealed that plastic systems could be delivered intact with little force when compared to fabric systems which tore in response to a significantly greater force. In addition, as plastic bags are nonporous, cells from neoplastic lesions are less like to leak thus reducing the risk of tumour seeding.[9]

Above all, a major shortcoming associated with these retrieval systems is the cost. The cost factor does come into play in third world scenarios where the surgeons have to work with limited resources while maintaining the oncological principles and avoid compromising the quality of care. The cost of these retrieval systems ranges from $25 to 100; thus, increasing the cost of surgery to an extent discouraging the patients from opting for minimal access modality.

Keeping all these aspects in mind, we designed a retrieval bag as an economical option for specimen extraction. The ureteric catheter placed in the tunnel of the bag helps to keep the mouth of the bag open owing to its inherent stiffness with certain degree of malleability. This eases the entrapment of the specimen without the worry of edges of the bag folding inside. The bag being made of transparent plastic and sealed with an autoseal device ensures intact specimen retrieval without the risk of tumour seeding. The retrieval system does not require any separate introducer sheath for deployment or any additional ports for manoeuvring. Finally, the entire cost of making one bag turned out to be $1.20.

These observations do show the potential impact of this innovation can have in benefitting a large number of patients, especially from the underprivileged sections of the society. These are the patients for whom cost of a procedure is a factor that dictates whether he/she will opt for medical intervention or not.

Furthermore, the statistical analysis in this study clearly shows that the experience of the surgeon (expert or novice) did not have an impact on the retrieval time of the specimen. This finding suggests that the use of our retrieval system did not require the surgeons to undergo a steep learning curve.

CONCLUSION

Among the commercially available retrieval systems, our design of retrieval system offers a cost-effective option which is easy to make, without the risk of tumour seeding and the need for separate access sheath. It's a retrieval system which has proved its efficacy in laparoscopic as well as robotic procedures with no bearing on the expertise of the surgeon involved. Thus Modified Nadiad Bag can be an option worth considering in circumstances where the cost of surgery matters as much as the quality of surgery.

Limitations of the study

Any device or technique of procedure, when introduced into clinical practice is pitched against a gold standard device or technique. Similarly, there is a need for the nadiad bag to be compared to a retrieval system already available in the market to test its efficiency

We acknowledge that the study was a retrospective one. A two-arm prospective study with an equal number of participants in expert group and novice group would be a more scientifically ideal way of knowing if the expertise of the surgeon does have a bearing in using this retrieval system or not.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Independent samples test
	Levene’s test for equality of variances		t-test for equality of means
	F	Sig.	t	df	Sig. (2-tailed)	Mean difference	Std. Error difference	95% confidence interval of the difference
	Lower	Upper	Lower	Upper	Lower	Upper	Lower	Upper	Lower
Retr_Time
Equal variances assumed	2.367	0.126	-1.248	166	0.214	-26.226	21.018	-67.722	15.271
Equal variances not assumed			-1.063	47.944	0.293	-26.226	24.678	-75.846	23.395
Organ_Size
Equal variances assumed	9.255	0.003	0.178	166	0.859	2.060	11.602	-20.847	24.967
Equal variances not assumed			0.205	73.828	0.838	2.060	10.039	-17.943	22.063
Spec_Wt
Equal variances assumed	0.222	0.638	-0.005	166	0.996	-0.255	53.357	-105.600	105.091
Equal variances not assumed			-0.004	51.175	0.997	-0.255	58.864	-118.419	117.909