Identification of polysubstance abuse in the parturient

D. J. Birnbach*, I. M. Browne, A. Kim, D. J. Stein and D. M. Thys

Departments of Anesthesiology and Obstetrics and Gynecology, St Luke’s-Roosevelt Hospital Center, College of Physicians and Surgeons of Columbia University, 1000 Tenth Ave., New York, NY 10019, USA*Corresponding author

Accepted for publication: April 11, 2001


    Abstract
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
Illicit drugs are widely used by inner city patients and their use by pregnant women has increased in recent years. The aim of this study was to determine the prevalence of polysubstance abuse among parturients at our institution who received no prenatal care (‘unbooked’) and to determine the accuracy of the Ontrak TesTcupTM an in vitro immunodiagnostic assay. We prospectively analysed urine from 50 ‘unbooked’ parturients and found that 26 (52%) tested positive for cocaine. Of these, six patients (23%) were also positive for morphine. All TesTcupTM results were confirmed by the hospital laboratory using alternate chemical methods. When comparing TesTcupTM to the hospital laboratory, there were no false positive or negative results. Given the high frequency of concomitant opioid abuse in cocaine-abusing parturients, anyone suspected of cocaine abuse should be tested for other illicit substances. TesTcupTM is a clinically accurate test that allows the rapid assessment of several drugs of abuse, which may impact on anaesthetic care.

Br J Anaesth 2001; 87: 488–90

Keywords: complications, polysubstance abuse; pregnancy, polysubstance abuse


    Introduction
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
Illicit substance abuse among women of reproductive age has increased over the past decade.1 Patients who have received no prenatal care (‘unbooked’) are at the highest risk for substance abuse. For example, the prevalence of antepartum cocaine use among ‘unbooked’ parturients at a hospital in New York City was reported to be 68%.2 Pregnant women who use illicit drugs may be more likely to use a combination of drugs rather than a single drug.3 The aim of this study was to determine the prevalence of polysubstance abuse among unregistered parturients at our institution and to evaluate the accuracy of a screening test (TesTcupTM) that would provide simultaneous toxicology results for several drugs of abuse.


    Methods and results
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
The official policy of this hospital is to perform mandatory urine toxicology testing on all ‘unbooked’ patients admitted to our maternity unit. The patients are informed of this policy and that these results will become part of their hospital record. The results will be used by physicians as well as social workers to assist in discharge planning for the baby. In this study, toxicology testing was limited to these ‘unbooked’ patients, as they are easily identifiable and at high risk for antepartum drug abuse.2

Following Institutional Review Board approval, urine from 50 consecutively admitted ‘unbooked’ parturients that was being sent to the hospital laboratory for toxicology testing was also tested by one anaesthetist using the Ontrak TesTcupTM (Roche Diagnostic Systems, Branchburg, NJ, USA). This is a qualitative assay for cocaine metabolite (benzoylecgonine), opioids (morphine and its derivatives), amphetamine, tetrahydrocannabinol (THC), and phencyclidine (PCP), a ketamine-like drug. Toxicology results obtained by the anaesthetist were compared with those of the hospital laboratory, performed by enzyme immunoassay techniques according to manufacturer’s specifications.

The TesTcupTM comprises immunochromatographic reagents that qualitatively and simultaneously detect the presence of illicit substances or their metabolites in the urine. It is based on the competition between the drug and the immobilized drug conjugate in the sample for anti-drug antibodies coated on blue-dyed microparticles. Each drug assay has its own immunochromatographic strip, which contains an antibody specific for each illicit substance or metabolite.4 In approximately 3–5 min, a control reading for each substance is automatically performed and appears in the lower part of the result panel on the front of the cup. Following this, the various toxicology results can be easily read by the presence or absence of blue bands in the result window, similar to those used in commonly available over-the-counter pregnancy tests. The cost of each TesTcupTM is approximately 20.00 US dollars. The anaesthetist performing the assay was blinded to the results of the hospital laboratory. The TesTcupTM and hospital test results were compared by kappa analysis.

Of the 50 urine samples analysed by the TesTcupTM, 26 (52%) were positive for cocaine, seven (14%) were positive for opioids, four (8%) were positive for amphetamines, four (8%) were positive for THC, and one (2%) was positive for PCP. Of the 26 samples positive for cocaine, six (23%) were also positive for opioids, four (15%) were positive for amphetamines, two (8%) were positive for THC, and one (4%) was positive for PCP (Fig. 1). These results were all confirmed by testing in the hospital laboratory, with no false positive or false negative results (kappa=1). All patients who tested positive for opioids denied opioid use, and 13 of the 26 patients whose samples tested positive for cocaine denied cocaine use. As none of the opioid positive parturients had evidence of needle marks, it is likely that the opioids were combined with other illicit agents and smoked or taken orally.



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Fig 1 Profile of polysubstance abuse in ‘unbooked’ parturients (n=50). THC=tetrahydrocannabinol; PCP=phencyclidine.

 

    Comment
 Top
 Abstract
 Introduction
 Methods and results
 Comment
 References
 
Identification of the substance-abusing parturient presents a challenge as denial of such abuse is common and clinical signs of illicit drug use can mimic other diseases such as pre-eclampsia.5 In our study, 52% of the unregistered parturients who were admitted to the maternity unit tested positive for cocaine, and of these 23% also tested positive for opioids. The majority of parturients who tested positive for illicit drugs denied substance abuse. Our findings are consistent with the results of previous studies that screened either parturients or neonates for illicit substances.6 7

Although knowledge of cocaine abuse in the parturient is vital to the anaesthetist,2 information regarding opioid abuse is equally important. Parturients requesting analgesia in labour are increasingly likely to receive spinal or epidural opioids. If side effects of this treatment occur, antagonist or agonist-antagonist agents may be administered. In addition, agonist-antagonist agents such as nalbuphine and butorphanol are sometimes administered for analgesia in labour. The administration of these drugs represents a potential hazard for the unidentified opioid-dependent parturient as they can precipitate acute maternal and/or fetal withdrawal syndrome.8

Because of the potential obstetric and anaesthetic implications of drug abuse, all parturients considered to be ‘high risk’ should be tested with a method that allows for prompt results. Hospitals with toxicology screening procedures often analyse samples using gas chromatography/mass spectrometry or thin-layer chromatography, and fluorescence polarization immunoassays. While these are extremely accurate methods, results may not be available for more than 24 h, depending on hospital facilities. This is generally too late to be of benefit to the anaesthetist caring for these patients.

We evaluated a rapid and inexpensive screening test that was found to identify illicit substances that had been ingested within the previous 72 h. The TesTcupTM has been shown to be an accurate assay9 and has been utilized by many specialties and in emergency situations.10 In this study, an anaesthetist without special training in toxicology testing was able to complete the tests in less than 5 min with results identical to those reported by the hospital laboratory. It should be noted, however, that latex agglutination tests do not provide a quantitative analysis. Although a positive result identifies patients who have ingested specific illicit drugs up to 72 h before testing, these tests cannot quantify the amount of drug or identify the time of last ingestion. Rather, the TesTcupTM identifies either drug or drug metabolites only if they have reached a predetermined cut-off level. As the half-life of cocaine, is only minutes in duration, benzoylecgonine, a longer acting primary metabolite of cocaine is used for detection of this drug. It is possible that below the cut-off limits, TesTcupTM results might be negative despite presence of low levels of drug or drug metabolite. However, at such levels, clinical significance is questionable. When time allows, recognized laboratory testing for drugs of abuse is optimal. However, when toxicology results are necessary in an emergency situation such as the parturient in active labour, immunodiagnostic assays such as the TesTcupTM can provide accurate information that can be used by the anaesthetist to provide optimal care.


    Acknowledgements
 
We are grateful to Roche Diagnostic Systems for supplying the TesTcupTM kits.


    References
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 Abstract
 Introduction
 Methods and results
 Comment
 References
 
1 Kaltenbach K, Berghella V, Finnegan L. Opioid dependence during pregnancy: effects and management. Obst Gyn Clin 1998; 25: 139–51

2 Birnbach DJ, Stein DJ, Grunebaum A, et al. Cocaine screening of parturients without prenatal care: an evaluation of a rapid screening assay. Anesth Analg 1997; 84: 76–9[Abstract]

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5 Towers CV, Pircon RA, Nageotte MP, et al. Cocaine intoxication presenting as pre-eclampsia and eclampsia. Obstet Gynecol 1993; 81: 545–7[Abstract]

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7 Ostrea EM, Ostrea AR, Simpson PM. Mortality within the first 2 years in infants exposed to cocaine, opiate, or cannabinoid during gestation. Pediatrics 1998; 100: 79–83[Abstract/Free Full Text]

8 Weintraub SJ, Naulty JS. Acute abstinence syndrome after epidural injection of butorphanol. Anesth Analg 1985; 64: 452–3[ISI][Medline]

9 Schilling RF, Bidassie B, El-Bassel N. Detecting cocaine and opiates in urine: comparing three commercial assays. J Psychoactive Drug 1999; 31: 305–13

10 Westdorp EJ, Salomone JA, Roberts DK, et al. Validation of a rapid urine screening assay for cocaine use among pregnant emergency patients. Academic Emerg Med 1995; 2: 795–8